Star Macromolecules for Personal and Home Care

ABSTRACT

A polymer composition comprising star macromolecules is provided. Each star macromolecule has a core and five or more arms, wherein the number of arms within a star macromolecule varies across the composition of star molecules. The arms on a star are covalently attached to the core of the star; each arm comprises one or more (co)polymer segments; and at least one arm and/or at least one segment exhibits a different solubility from at least one other arm or one other segment, respectively, in a reference liquid of interest.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/926,143, filed Oct. 27, 2010, which is a continuation-in-part of U.S.application Ser. No. 12/799,411, filed Apr. 23, 2010, which furtherclaims priority under 35 USC §119(e) to U.S. Provisional Application No.61/214,397, filed Apr. 23, 2009. All of the foregoing relatedapplications, in their entirety, are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to multi-arm star macromolecules which areused as rheology modifiers, including use in the cosmetic, personal careand home care compositions.

BACKGROUND AND PRIOR ART

Most personal care products on the market contain many types of polymersthat vary by structure, chemistry, and raw material source (synthetic ornatural) that are combined to provide products with many differentdesired functions. One class of polymer additives is targeted ataltering or modifying the rheological properties of the product that arevery important for consumer appeal. Often, additives that providesufficient viscosity are needed, especially for those formulations wherethe viscosity without additives is close to that of the pure solvent(water). However, merely increasing viscosity is not sufficient, and inreality, the modifiers should be selected to provide certain desiredrheological properties for the formulation that depend on its nature,the mode of delivery, type of flow, and the aesthetic appeal of finalapplication. Typically, low molecular weight surfactants are used tomodify rheological properties but they have to be used at largeconcentrations. Resulting in relatively high cost, and an adverse impacton the environment (e.g., water pollution).

The thickeners used in cosmetic and body care preparations have to meetstringent requirements. First and foremost, they have to show highcompatibility and also—if possible—biodegradability so that manysubstances have to be ruled out from the outset for use in cosmetics. Inaddition, they should be universally useable in aqueous, emulsoidal,alcoholic and oil-containing bases, be readily processable and lead to arheology which enables the product to be easily applied so that thepreparations can be removed and distributed under clean and simpleconditions.

Thickeners that are designed molecular level to provide the desiredproperties would be expected to be compatible with many otherauxiliaries, more particularly with salts and surfactants. The thickeneritself and the other auxiliaries should also lend themselves to readyincorporation into the formulation. The thickened preparations are alsoexpected to show stable rheology and an unchanging physical and chemicalquality even in the event of long-term storage and changes in pH andtemperature. Finally, the thickeners should be inexpensive to producewithout causing significant environmental pollution.

In view of this complex requirement profile, it is clear why, eventoday, there is still a demand for new thickeners in the cosmeticsfield.

SUMMARY OF THE INVENTION

Accordingly, in one aspect the invention provides a polymer compositioncomprising star macromolecules, each star macromolecule having a coreand five or more arms, wherein the number of arms within a starmacromolecule varies across the composition of star molecules; and thearms on a star are covalently attached to the core of the star; each armcomprises one or more (co)polymer segments; and at least one arm and/orat least one segment exhibits a different solubility from at least oneother arm or one other segment, respectively, in a reference liquid ofinterest.

The use of the polymer composition in personal care products and homecare products is also provided.

In one aspect of the invention, there is a process of forming a miktostar macromolecule comprising:

i) creating a reaction mixture comprising a plurality of first polymericsegments having an ATRP-functional terminal group and a plurality ofsecond monomers, wherein at least a portion of the first polymericsegments are formed by polymerizing a plurality of first monomers,non-limiting examples of first monomers include hydrophobic monomers;ii) forming a second polymeric segment extending from said firstpolymeric segment by activating the ATRP-functional terminal group onsaid first polymeric segment to initiate polymerization of a portion ofthe second monomers, to form a plurality of block copolymeric arms;iii) during the polymerization of the second monomers, introducing aplurality of second monomer initiators having an ATRP functionalterminal group into the reaction mixture;iv) activating the ATRP-functional terminal group on said second monomerinitiator to initiate polymerization of a second portion of the secondmonomer, to form a plurality of homopolymeric arms; andv) crosslinking at least a portion of the block copolymeric arms and atleast a portion of the homopolymeric arms to form at least one miktostar macromolecule.

In one aspect of the invention, there is a star macromolecule that formsa gel when dissolved in water at a concentration of at least 0.2 wt. %and is formed by:

i) creating a reaction mixture comprising a plurality of first polymericsegments having an ATRP-functional terminal group and a plurality ofsecond monomers, wherein at least a portion of the first polymericsegments are formed by polymerizing a plurality of first monomers;ii) forming a second polymeric segment extending from said firstpolymeric segment by activating the ATRP-functional terminal group onsaid first polymeric segment to initiate polymerization of a portion ofthe second monomers, to form a plurality of block copolymeric arms;iii) during the polymerization of the second monomers, introducing aplurality of second monomer initiators having an ATRP functionalterminal group into the reaction mixture;iv) activating the ATRP-functional terminal group on said second monomerinitiator to initiate polymerization of a second portion of the secondmonomer, to form a plurality of homopolymeric arms; andv) crosslinking at least a portion of the block copolymeric arms and atleast a portion of the homopolymeric arms;wherein:a) the gel has a dynamic viscosity of at least 20,000 cP; andb) the star macromolecule has a molecular weight of 150,000 g/mol and600,000 g/mol.

In one aspect of the invention, there is a star macromolecule polymercomposition comprising one or more star macromolecules prepared by animproved, efficient arm-first living-controlled radical polymerizationmethod, wherein the one or more star macromolecules are represented byFormula X:

[(P1)_(q1)-(P2)_(q2)]_(t)-Core-[(P3)_(q3)]_(r)

wherein:Core represents a crosslinked polymeric segment;P1 represents a hydrophobic homopolymeric segment comprised of repeatunits of monomeric residues of polymerized hydrophobic monomers;P2 represents a hydrophilic homopolymeric segment comprised of repeatunits of monomeric residues of polymerized hydrophilic monomers;P3 represents a hydrophilic homopolymeric segment comprised of repeatunits of monomeric residues of polymerized hydrophilic monomers;q1 represents the number of repeat units in P1 and has a value between 1and 50;q2 represents the number of repeat units in P2 and has a value between30 and 500;q3 represents the number of repeat units in P3 and has a value between30 and 500;r represents the number of homopolymeric arms covalently attached to theCore;t represents the number of copolymeric arms covalently attached to theCore; andwherein the molar ratio of r to t is in the range of between 20:1 and2:1.

In one aspect of the invention, there is a star macromolecule having amolecular weight of between 150,000 g/mol and 600,000 g/mol that forms aclear homogeneous gel when dissolved in water at a concentration of atleast 0.2 wt. % wherein the gel has:

i) a dynamic viscosity of at least 20,000 cP;ii) a salt-induced break value of at least 60%;iii) a pH-induced break value of at least 80%;iv) a shear-thinning value of at least 10; and/orv) an emulsion value of >12 hours.

In one aspect of the invention, there is a clear homogeneous gel,comprising a star macromolecule having a molecular weight of between150,000 g/mol and 600,000 g/mol, comprises the following properties:

i) a dynamic viscosity of at least 20,000 cP;ii) a salt-induced break value of at least 60%;iii) a pH-induced break value of at least 80%;iv) a shear-thinning value of at least 10; and/orv) an emulsion value of >12 hours;wherein the clear homogeneous gel is formed when the star macromoleculeis dissolved in water at a concentration of at least 0.2 wt. %.

In one aspect of the invention, there is an emulsifier-free emulsioncomprising:

a water-soluble star macromolecule having:i) molecular weight of at least 150,000 g/mol; andii) a dynamic viscosity of at least 20,000 cP at a concentration of 0.4wt. %.

In one aspect of the invention, there is an emulsion comprising:

a water-soluble star macromolecule having:i) a molecular weight of at least 150,000 g/mol; andii) a dynamic viscosity of at least 20,000 cP at a concentration of 0.4wt. %.

In one aspect of the invention, there is a thickening agent that forms aclear homogeneous gel when dissolved in water at a concentration of atleast 0.2 wt. %,

wherein the gel has:i) a dynamic viscosity of at least 20,000 cP;ii) a salt-induced break value of at least 60%;iii) a pH-induced break value of at least 80%;iv) a shear-thinning value of at least 10; and/orv) an emulsion value of greater than 12 hours.

In one aspect of the invention, the star macromolecule, emulsfier, gel,emusilfier-free emulsion, emulsion and/or thickening agent, includingthose formed by the one-pot process, ATRP, CRP, and/or combinations ofone or more of these processes, may be used to provide a certain levelof control over viscosity and consistency factors in many aqueous andoil based systems including, for example, water- and solvent-basedcoating compositions, paints, inks, antifoaming agents, antifreezesubstances, corrosion inhibitors, detergents, oil-well drilling-fluidrheology modifiers, additives to improve water flooding during enhancedoil recovery, dental impression materials, cosmetic and personal careapplications including hair styling, hair sprays, mousses, hair gels,hair conditioners, shampoos, bath preparations, cosmetic creams,cosmetic gels, lotions, ointments, deodorants, powders, skin cleansers,skin conditioners, skin emollients, skin moisturizers, skin wipes,sunscreens, shaving preparations, and fabric softeners.

In one aspect of the invention, there is a macromolecule, comprising: aplurality of arms comprising at least two types of arms, wherein afirst-arm-type extends beyond a second-arm-type and said first-arm-typehas a hydrophobic segment on its distal end, wherein at least a portionof the hydrophobic segment may extend beyond the length of thesecond-arm-types either by the size of the monomeric segment or segments(which may be varied by length of monomeric residue, degree ofpolymerization, and/or both) for which the hydrophobic segment isattached. Recognizing that the “length” of an arm or segment and the“extending beyond” limitation may be theoretical, meaning that while itis not emperically measured it is understood to “extend beyond” and/orhave a longer “length” relative to the length of the second-arm-type ifthe degree of polymerization is greater for monomeric residues of thesame type or of the same theoretical length.

In one aspect of the invention, there is a star macromolecule,comprising: a plurality of arms comprising at least two types of arms,wherein the degree of polymerization of a first-arm-type is greater thanthe degree of polymerization of a second-arm-type, and wherein saidfirst-arm-type has a distal end portion that is hydrophobic. In anotheraspect of the invention, this star macromolecule may be formed by firstforming or obtaining the hydrophobic portion and then forming theremaining portion of the first-arm-type from the end of the hydrophobicportion and the second-arm-type in a one-pot synthesis wherein thepoylmerization of the second portion of the first-arm-type is commencedprior to the initialization of the second-arm-type but there is at leastsome point wherein portions, e.g., substantial portions, of thefirst-arm-type and second-arm-type are being polymerically extendedsimultaneously.

In one aspect of the invention, there is an oil-soluble starmacromolecule, comprising: a plurality of different arms comprising atleast two types of arms, wherein a first-arm-type extends beyond asecond-arm-type and said first-arm-type has a hydrophilic segment on itsdistal end.

In one aspect of the invention, there is an oil-soluble starmacromolecule, comprising: a plurality of arms comprising at least twotypes of arms, wherein the degree of polymerization of a first-arm-typeis greater than the degree of polymerization of a second-arm-type, andwherein said first-arm-type has a hydrophilic segment on its distal end.

In one aspect of the invention, there is a star macromolecule,comprising: a plurality of arms comprising at least two types of arms,wherein the degree of polymerization of a first-arm-type is greater thanthe degree of polymerization of a second-arm-type, and wherein saidfirst-arm-type has a distal end portion that is hydrophobic and theproximal portion of the first-arm-type and second-arm-type are the samewith the only difference between the first-arm-type and thesecond-arm-type being that the first-arm-type has a hydrophobic portionon its distal end. In another aspect of the invention, this starmacromolecule may be formed by first forming or obtaining thehydrophobic portion and then forming the remaining portion of thefirst-arm-type from the end of the hydrophobic portion and thesecond-arm-type simultaneously in a one-pot synthesis.

In an aspect of the invention, the star macromolecules may have an HLMof greater than 0.85, for example greater than 0.87. or 0.9 or 0.93 or0.95 or 0.97 or 0.98.

In an aspect of the invention, the star macromolecules may have acalculated HLM of greater than 0.85, for example greater than 0.87. or0.9 or 0.93 or 0.95 or 0.97 or 0.98 and a viscosity of greater than60,000 cP at a pH between 7 to 10.5 and a molecular weight of between200,000 g/mol and 550,000 g/mol and a shear-thinning value of at least10 and, optionally, a salt-induced break value of at least 60%.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention may be betterunderstood by reference to the accompanying Figures, in which:

FIG. 1: Illustration of the structure of a segmented homo-arm starmacromolecule and two different types of mikto-arm star macromolecules.

FIG. 2: GPC curve for the polystyrene macroinitiator formed in step 1 ofthe synthesis of an exemplary (PSt-b-PAA) star macromolecule.

FIG. 3: GPC curves for the polystyrene macroinitiator formed in step 1of the synthesis of an exemplary (PSt-b-PAA) star macromolecule and GPCcurve for block copolymer formed after chain extension with tBA in step2 of the synthesis.

FIG. 4: GPC curves of the PSt-b-tBA block copolymer and the starmacromolecule formed after core formation reaction is step 3 of theformation of an exemplary (PSt-b-PAA) star macromolecule.

FIG. 5: Image showing the thickening properties of (PSt-b-PAA) starmacromolecule.

FIG. 6: Viscosity of aqueous solution of (PSt-b-PAA) star macromoleculevs. shear rate.

FIG. 7: Viscosity of aqueous solution of (PSt-b-PAA) star macromoleculevs. concentration.

FIG. 8: Viscosity of an aqueous solution and a water/windex (1/1 v/v)solution of (PSt-b-PAA) star macromolecule vs. shear rate.

FIG. 9: Viscosity of an aqueous solution and a water/windex (1/1 v/v)solution of Carbopol EDT 2020 vs. shear rate.

FIG. 10: GPC Curves for preparation of the precursor to a PAA star.Solid line PtBA M_(n)=18,900 PDI=1.14; Dashed line (PtBA)_(X) star withM_(n,app) 112,600 PDI=1.36

FIG. 11: Viscosity of aqueous solution of (PSt-b-PAA) star macromoleculeand (PAA) star macromolecule vs. shear rate.

FIG. 12: Images demonstrating the emulsifying properties of (PSt-b-PAA)star macromolecule.

FIG. 13: Synthesis of [(PSt-b-PtBA)/(PtBA)] star macromolecule usingarm-first method.

FIG. 14: GPC curves for C₁₈-PtBA arm star macromolecule, Solid lineC₁₈-PtBA arm with M_(n)=19,200 PDI=1.16; dashed line (C₁₈-PtBA)_(X) starmacromolecule M_(n,app)=95,600 PDI=1.48.

FIG. 15. GPC curves for C₁₂-PtBA arm star macromolecule, Solid LineC₁₂-PtBA M_(n)=17,500 PDI=1.22; Dashed line (C₁₂-PtBA)_(X) M_(n,app)113,900 PDI=1.53.

FIG. 16: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying thickening agent weight %.

FIG. 17: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying shear rates.

FIG. 18: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying NaCl weight %.

FIG. 19: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying pH.

FIG. 20: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying H₂O₂ weight %.

FIG. 21: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying temperatures.

FIG. 22: is a graph comparing viscosity of Advantomer and Carbopol ETD2020 at varying NaCl weight %.

FIG. 23: GPC curves for the reaction product resulting from step 2 ofExample 9.

FIG. 24: GPC curves for the reaction product resulting from step 3 ofexample 9.

DETAILED DESCRIPTION OF THE INVENTION

The term “solubility” or “soluble” is understood to mean that when acomponent is mixed into a solvent and tested, at STP in a 1 cm cuvette,it has a light transmittance value, at a wavelength at or around aUV/Vis minimum wavelength for the mixture, of at least 40%, for example,at least 50%, 70%, 85%, or at least 95%.

The term “clear” as is used to describe a homogenous gel or homogenoussolution is understood to mean that when the gel or solution is tested,at STP in a 1 cm cuvette, it has a light transmittance value, at awavelength at or around a UV/Vis minimum wavelength for the gel orsolution, of at least 40%, for example, at least 50%, 70%, 85%, or atleast 95%.

The term “water-soluble monomer” is understood to mean a monomer havingat least about 10 wt. % solubility in water at STP. For example, a watersoluble monomer may have at least 15 wt. %, 20 wt. %, 25 wt. %, or atleast 30 wt. % solubility in water at STP.

The term “water-insoluble monomer” is understood to mean a monomerhaving less water solubility than a water soluble monomer, for example,less that about 5 wt. %, such as less than 1 wt. % or 0.5 wt. %solubility in water at STP.

The term “water-soluble star macromolecule” is understood to mean a starmacromolecule that is soluble in water, pH adjusted if necessary to a pHof no greater than 8 with sodium hydroxide, at a concentration of atleast 5 g/L, for example, between 8 g/L to 100 g/L, such as, at least 10g/L, 12 g/L, 15 g/L, or at least 20 g/L. For example, a water-solublestar macromolecule having an aqueous solubility of at least 10 g/L mayinclude the introduction of at least 10 g of the star macromolecule intoapproximately 1 L of water, neutralizing the mixture, if necessary, byadjusting the pH of the resulting mixture to about pH 8 (e.g., with theaddition of base, such as sodium hydroxide), and vigorously stirring ata temperature no greater than 100° C. for no more than about 60 minutes,to achieve dissolution of the star macromolecule, and testing thesolubility at STP.

The term “oil-soluble star macromolecule” is understood to mean a starmacromolecule that is soluble in mineral oil at a concentration of atleast 5 g/L, for example, between 8 g/L to 100 g/L, such as, at least 10g/L, 12 g/L, 15 g/L, or at least 20 g/L of mineral oil. For example, anoil-soluble star macromolecule having an oil solubility of at least 10g/L may include the introduction of at least 10 g of the starmacromolecule into approximately 1 L of mineral oil, and vigorouslystirring at a temperature no greater than 100° C. for no more than about60 minutes, to achieve dissolution of the star macromolecule, andtesting the solubility at STP.

The term “hydrophilic” is understood to mean, in relation to a material,such as a polymeric arm, or a polymeric segment of a polymeric arm, thatthe material is water soluble and comprises hydrophilic segments havingan HLB equal to or greater than 8, for example, an HLB equal to 16-20,or equal to or greater than 18, 19, or 19.5. In certain embodiments, thehydrophilic segment may comprise at least 75 mol % of water-solublemonomer residues, for example, between 80 mol % to 100 mol % or at least85 mol %, 90 mol %, 95 mol %, or at least 97 mol % water-soluble monomerresidues.

The term “hydrophobic” is understood to mean, in relation to a material,such as a polymeric arm, or a polymeric segment of a polymeric arm, thatthe material is water insoluble and comprises hydrophobic segmentshaving an HLB less than 8, for example, an HLB less than 7. In certainembodiments, the hydrophobic segment may comprise at least 75 mol % ofwater-insoluble monomer residues, for example, between 80 mol % to 100mol % or at least 85 mol %, 90 mol %, 95 mol %, or at least 97 mol %water-insoluble monomer residues.

The term “monomer residue” or “monomeric residue” is understood to meanthe residue resulting from the polymerization of the correspondingmonomer. For example, a polymer derived from the polymerization of anacrylic acid monomer (or derivatives thereof, such as acid protectedderivatives of acrylic acid including but not limited to methyl ort-butyl ester of acrylic acid), will provide polymeric segments,identified as PAA, comprising repeat units of monomeric residues ofacrylic acid, i.e., “—CH(CO₂H)CH₂—”. For example, a polymer derived fromthe polymerization of styrene monomers will provide polymeric segments,identified as PS, comprising repeat units of monomeric residues ofstyrene, i.e., “—CH(C₆H₅)CH₂—.” For example, a polymer derived from thepolymerization of monomeric divinylbenzene monomers will providepolymeric segments comprising repeat units of monomeric residues ofdivinylbenzene, i.e., “—CH₂CH(C₆H₅)CHCH₂—.”

The term “emulsifier” is understood to mean a component that comprisesan appreciable weight percent of an amphiphilic compound having amolecular weight of less than 5,000 MW. Emulsifiers are usually linearorganic compounds that contain both hydrophobic portions (tails) andhydrophilic portions (heads), i.e., are amphiphilc. Examples ofemulsifiers include but are not limited to: alkyl benzenesulfonates,alkanesulfonates, olefin sulfonates, alkylethersulfonates, glycerolether sulfonates, .alpha.-methyl ester sulfonates, sulfofatty acids,alkyl sulfates, fatty alcohol ether sulfates, glycerol ether sulfates,hydroxy mixed ether sulfates, monoglyceride (ether) sulfates, fatty acidamide(ether) sulfates, mono- and dialkylsulfosuccinates, mono- anddialkylsulfosuccinamates, sulfotriglycerides, ether carboxylic acids andsalts thereof, fatty acid isethionates, fatty acid sarcosinates, fattyacid taurides, acyl lactylates, acyl tartrates, acyl glutamates, acylaspartates, alkyl oligoglucoside sulfates, protein fatty acidcondensates (particularly wheat-based vegetable products) andalkyl(ether)phosphates, alkylbetaines, alkylamidobetaines,aminopropionates, aminoglycinates, imidazoliniumbetaines andsulfobetaines.

The term “emulsifier-free” is understood to mean a composition ormixture wherein the formulation is substantially devoid of anyemulsifiers, for example less than 0.1 wt. % of emulsifier, relative tothe total composition, or less than 0.05 wt. % of emulsifier, relativeto the total composition, or less than 0.01 wt. % of emulsifier,relative to the total composition, or a formulation where there is noemulsifier.

The term “STP” is understood to mean standard conditions for temperatureand pressure for experimental measurements, wherein the standardtemperature is a temperature of 25° C. and the standard pressure is apressure of 1 atm.

Structure of the Polymer Composition

Multi-arm star macromolecules are shown schematically in FIG. 1

In one embodiment, the arms in a star macromolecule are comprised of twoor more (co)polymer segments selected to modify the rheology of thereference liquid of interest. The star macromolecule structure isrepresented by the following formula [F-(M1)_(p1)-(M2)_(p2)]_(n)-C

wherein

-   -   i. [F-(M1)_(p1)-(M2)_(p2)] represents an arm comprised of a        segmented (co)polymer chain wherein each (co)polymer segment,    -   ii. (M1)_(p1)- and (M2)_(p2)- are compositionally distinct        adjacent (co)polymer segments where each segment is comprised of        one or more monomers with homo, random, gradient or block        (co)polymer structure and where p1 and p2 represent the degree        of polymerization of each copolymer segment,    -   iii. F-represents an optionally functional group or mixture of        functional groups present on the arm chain-end,    -   iv. (M1)_(p1) is not soluble or not fully soluble in the        reference liquid of interest,    -   v. (M2)_(p2) is soluble or mostly soluble in the reference        liquid of interest,    -   vi. and C represents the crosslinked core of the star        macromolecule which is comprised of crosslinker (Mx),        crosslinker (Mx) and monomer (My), crosslinker (Mx) and (M2), or        a mixture of (Mx), (My) and (M2), and    -   vii. n represents the average number of arms covalently attached        to the core of the star macromolecule.

In another embodiment, the star macromolecule structure can berepresented by the following formula,

[F-(M1)_(p1)-(M2)_(p2)]_(n)-C-[(M3)_(p3)-F]_(m)

wherein

-   -   i. [F-(M1)_(p1)-(M2)_(p2)] represents an arm comprised of a        segmented (co)polymer chain,    -   ii. (M1)_(p1)- and (M2)_(p2)- are compositionally distinct        adjacent (co)polymer segments where each segment is comprised of        one or more monomers with homo, random, gradient or block        (co)polymer structure and where p1 and p2 represent the degree        of polymerization of each copolymer segment,    -   iii. F- represents an optionally functional group or mixture of        functional groups present on the arm chain-end,    -   iv. (M1)_(p1) is not soluble or not fully soluble in the        reference liquid of interest,    -   v. (M2)_(p2) is soluble or mostly soluble in the reference        liquid of interest,    -   vi. and C represents the crosslinked core of the star        macromolecule which is comprised of crosslinker (Mx),        crosslinker (Mx) and monomer (My), crosslinker (Mx) and (M2), or        a mixture of (Mx), (My) and (M2), and    -   vii. n represents the average number of arms covalently attached        to the core of the star macromolecule,    -   viii. (M3)_(p3) is a (co)polymer segment which is comprised of        one or more monomers with homo, random, gradient or block        (co)polymer structure with a degree of polymerization p3 and    -   ix. m is the number of (M3)_(p3) (co)polymer arms covalently        attached to the core,    -   x. (M3)_(p3) is soluble or mostly soluble in the reference        liquid of interest and    -   xi. M2 and M3 can be comprised of the same or different        (co)monomers.

In a further embodiment, polymer composition comprises starmacromolecules in which the structure of a star can be represented bythe following formula,

[F-(M1)_(p1)]_(s)-C-[(M3)_(p3)-F]_(m)

wherein

-   -   i. [F-(M1)_(p1)-(M2)_(p2)] represents an arm comprised of a        segmented (co)polymer chain,    -   ii. (M1)_(p1)- is a (co)polymer segment where each segment is        comprised of one or more monomers with homo, random, gradient or        block (co)polymer structure with a degree of polymerization p1,    -   iii. F- represents an optionally functional group or mixture of        functional groups present on the arm chain-end,    -   iv. (M1)_(p1) is not soluble or not fully soluble in the        reference liquid of interest,    -   v. C represents the crosslinked core of the star macromolecule        which is comprised of crosslinker (Mx), crosslinker (Mx) and        monomer (My), crosslinker (Mx) and (M2), or a mixture, of (Mx),        (My) and (M2), and    -   vi. (M3)_(p3) is a (co)polymer segment which is comprised of one        or more monomers with homo, random, gradient or block        (co)polymer structure with a degree of polymerization p3 and    -   vii. (M3)_(p3) is soluble or mostly soluble in the reference        liquid of interest and    -   viii. m is the number of (M3)_(p3) (co)polymer arms covalently        attached to the core, and    -   ix. s is the average number of (M1)_(p1) (co)polymer arms        covalently attached to the core.

In an embodiment, the polymer composition, the number of arms on anyparticular star varies across the population of star macromolecules ineach composition, due to the synthetic process used for the synthesis ofthe composition. This process is called “arm first” method and isdescribed in details herein below. Due to variation in the number ofarms in star macromolecules, the number of arms n, m and s are referredas an average number of arms.

Star macromolecules with a single peak in the GPC curve with apolydispersity index (PDI) above 1.0 and below 2.5 is preferred.

As used herein, the term “reference liquid of interest” means the liquidto which the polymer composition will be added. Suitable examples ofreference liquids include, but are not limited to, water, oil or mixturethereof or water with additives which include but are not limited to;surfactants, oils, fats and waxes, emulsifiers, silicone compounds, UVprotectors, antioxidants, various water soluble substances, biogenicagents, deodorants, odor absorbers, antiperspirants, and germ and enzymeinhibitors. Such agents are disclosed in U.S. Pat. No. 6,663,855 andU.S. Pat. No. 7,318,929 and are herein incorporated by reference toprovide definitions for those terms.

Arms of a star can possess the same composition or be different (e.g.star macromolecule with formula (1) vs. (2) or (3), these star are shownin FIG. 1). The difference can be in composition or molecular weight orboth (e.g. different monomer units M1, M2, M3 and/or different degree ofpolymerization p1, p2, p3).

Term “(co)polymer” is defined as a polymer derived from two (or more)monomeric species (monomer units)

More preferred specific monomer units as a building blocks of M1, M2, M3and My include those selected from protected and unprotected acrylicacid, methacrylic acid, ethacrylic acid, methyl acrylate, ethylacrylate, .alpha.-butyl acrylate, iso-butyl acrylate, t-butyl acrylate,2-ethylhexyl acrylate, decyl acrylate, octyl acrylate, methylmethacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butylmethacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, decylmethacrylate, methyl ethacrylate, ethyl ethacrylate, n-butylethacrylate, iso-butyl ethacrylate, t-butyl ethacrylate, 2-ethylhexylethacrylate, decyl ethacrylate, 2,3-dihydroxypropyl acrylate,2,3-dihydroxypropyl methacrylate, 2-hydroxyethyl acrylate,2-hydroxypropyl acrylate, hydroxypropyl methacrylate, glycerylmonoacrylate, glyceryl monoethacrylate, glycidyl methacrylate, glycidylacrylate, acrylamide, methacrylamide, ethacrylamide, N-methylacrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide,N-ethyl acrylamide, N-isopropyl acrylamide, N-butyl acrylamide,N-t-butyl acrylamide, N,N-di-n-butyl acrylamide, N,N-diethylacrylamide,N-octyl acrylamide, N-octadecyl acrylamide, N,N-diethylacrylamide,N-phenyl acrylamide, N-methyl methacrylamide, N-ethyl methacrylamide,N-dodecyl methacrylamide, N,N-dimethylaminoethyl acrylamide, quaternisedN,N-dimethylaminoethyl acrylamide, N,N-dimethylaminoethylmethacrylamide, quaternised N,N-dimethylaminoethyl methacrylamide,N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate,quaternised N,N-dimethyl-aminoethyl acrylate, quaternisedN,N-dimethylaminoethyl methacrylate, 2-hydroxyethyl acrylate,2-hydroxyethyl methacrylate, 2-hydroxyethyl ethacrylate, glycerylacrylate, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate,2-methoxyethyl ethacrylate, 2-ethoxyethyl acrylate, 2-ethoxyethylmethacrylate, 2-ethoxyethyl ethacrylate, maleic acid, maleic anhydrideand its half esters, fumaric acid, itaconic acid, itaconic anhydride andits half esters, crotonic acid, angelic acid, diallyldimethyl ammoniumchloride, vinyl pyrrolidone vinyl imidazole, methyl vinyl ether, methylvinyl ketone, maleimide, vinyl pyridine, vinyl pyridine-N-oxide, vinylfuran, styrene sulphonic acid and its salts, allyl alcohol, allylcitrate, allyl tartrate, vinyl acetate, vinyl alcohol, vinylcaprolactam, vinyl acetamide, vinyl formamide and mixtures thereof.

Even more preferred monomer units as a building parts of M1, M2, M3 andMy are those selected from methyl acrylate, methyl methacrylate, methylethacrylate, ethyl acrylate, ethyl methacrylate, ethyl ethacrylate,n-butyl acrylate, n-butyl methacrylate, n-butyl ethacrylate,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexylethacrylate, N-octyl acrylamide, 2-methoxyethyl acrylate, 2-hydroxyethylacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethylmethacrylate, acrylic acid, methacrylic acid, N-t-butylacrylamide,N-sec-butylacrylamide, N,N-dimethylacrylamide, N,N-dibutylacrylamide,N,N-dihydroxyethyllacrylamide 2-hydroxyethyl acrylate, 2-hydroxyethylmethacrylate, benzyl acrylate, 4-butoxycarbonylphenyl acrylate, butylacrylate, 4-cyanobutyl acrylate, cyclohexyl acrylate, dodecyl acrylate,2-ethylhexyl acrylate, heptyl acrylate, iso-butyl acrylate,3-methoxybutyl acrylate, 3-methoxypropyl acrylate, methyl acrylate,N-butyl acrylamide, N,N-dibutyl acrylamide, ethyl acrylate, methoxyethylacrylate, hydroxyethyl acrylate, diethyleneglycolethyl acrylate, styrene(optionally substituted with one or more C.sub.1-C.sub.12 straight orbranched chain alkyl groups), alpha-methylstyrene, t-butylstyrene,p-methylstyrene, and mixtures thereof.

Monomer units within the arms may be connected with C—C covalent bonds.This is believed to make them hard to degrade so that the starmacromolecule may perform as efficient thickening agent in a harshenvironment (very high/low pH or in the presence of strong oxidizingagents).

When “C” represents the crosslinked core of the star macromolecule itmay be comprised of crosslinker (Mx), crosslinker (Mx) and monomer (My),crosslinker (Mx) and (M2), or a mixture of (Mx), (My) and (M2).

Suitable crosslinkers (Mx) encompass all of the compounds which arecapable, under the polymerization conditions, of bringing aboutcrosslinking. These include but are not limited di-, tri-,tetra-functional (meth)acrylates, di-, tri- and tetra-functionalstyrenes and other multi- or poly-functional crosslinkers.

Some examples of the crosslinking agents may include but are not limitedto 1,2-divinylbenzene, 1,3-divinylbenzene and 1,4-divinylbenzene,1,2-ethanediol di(meth)acrylate, 1,3-propanediol di(meth)acrylate,1,4butanediol di(meth)acrylate, 1,5-hexanediol di(meth)acrylate,divinylbenzene, ethyleneglycol di(meth)acrylate, propyleneglycoldi(meth)acrylate, butyleneglycol di(meth)acrylate, triethyleneglycoldi(meth)acrylate, polyethyleneglycol di(meth)acrylate,polypropyleneglycol di(meth)acrylate, polybutyleneglycoldi(meth)acrylate, and allyl(meth)acrylate, glycerol di(meth)acrylate,trimethylolpropane tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, allyl methacrylate, allyl acrylate.

The terms ‘mostly soluble’, ‘not fully soluble’, and ‘not soluble’ areused to describe the extent which a composition which is capable ofbeing dissolved in a reference liquid of interest.

The term ‘mostly soluble’ is used to describe a composition which iscapable dissolves completely with exception of a slight cloudiness inthe reference liquid of interest. The term ‘not fully soluble’ is usedto describe a composition which disperses with a cloudiness in thereference liquid of interest. The term ‘not soluble’ is used to describea composition which does not disperse and remains as a solid in thereference liquid of interest. A list of solvents and non-solvent forpolymers can be found in “Polymer Handbook, 4^(th) Ed.” edited byBrandrup J.; Immergut, Edmund H.; Grulke, Eric A.; Abe, Akihiro; Bloch,Daniel R., John Wiley & Sons: 2005.

Multi-arm stars macromolecules are the preferred topology for anembodiment of the present invention as they can adopt a globular shapewherein the inner segment, (M2)_(p2) of each arm covalently attached tothe core, can chain extend in a selected solvent to attain a highlyswollen stable structure. The dispersant medium can be water, oil ormixture thereof. The degree of polymerization p2 of the segment (M2),should be higher than that of p1 of segment (M1) to attain a highlyswollen stable structure. A star macromolecule with p2>(3×p1) is morepreferred.

In one embodiment, a star macromolecule described with formula (2) andshown in FIG. 1B, comprising a fraction of segmented (co)polymer arms[F-(M1)_(p1)-(M2)_(p)2], the average number of arms, n, should begreater than two per star, preferentially greater than three, and cancomprise a mole fraction between 0.5 and 100% of the arms in the averagestar macromolecule. The ratio of n to m is more preferably between 100and 0.1.

In one embodiment, in a star macromolecule described with formula (3)and shown in FIG. 1C comprising a fraction of arms [F-(M1)_(p1)] theaverage number of arms, o, should be greater than two per star,preferentially greater than three, and can comprise a mole fractionbetween 0.5 and 100% of the arms in the average star macromolecule. Theratio of o to m is more preferably between 100 and 0.1.

An embodiment of the present invention can be exemplified by a multi-armstar macromolecule wherein the average number of arms in the starmacromolecule is between 5 and 500, preferentially between 10 and 250.

In one embodiment, the star macromolecule has a core which containsadditional functionality and/or expanded free volume. ‘Expended freevolume’ of the core is defined as the core with lower crosslink density.The free volume in the core is generated when during the crosslinkingprocess crosslinker Mx with monomer M2 or My is used. If M2 or My aremonomers with functional groups, these groups will be incorporated inthe core.

In one embodiment, the star macromolecule may store and release incontrolled rate the small molecules. ‘Small molecules’ are fragrances,UV absorbers, vitamins, minerals, dyes, pigments, solvents, surfactants,metal ions, salts, oils, or drugs. These small molecules can be storedinside the core of the star macromolecule and next released. Each smallmolecule has some affinity to the core, is soluble in the coreenvironment. Higher affinity of the small molecule to the core willresult in the lower rate of release from star macromolecule. Theaffinity may be increased or decreased through non-covalent forcesincluding H-bonding, electrostatic, hydrophobic, coordination and metalchelating interactions.

In one embodiment, the star macromolecule displays shear thinningbehavior. ‘Shear thinning’ is defined as is an effect where viscositydecreases with increasing rate of shear stress. The extent of shearthinning behavior is characterized using a Brookfield-type viscometerwhere viscosities are measured under different shear rates.

In one embodiment, the star macromolecule comprises a functional groupwhich exhibits H-bonding, coordination, hydrophobic, metal chelatingand/or electrostatic forces. “F” represents an optionally functionalgroup or mixture of functional groups present on the arm chain-end.Functional groups (F) encompass all of the compounds capable ofinteracting through non-covalent forces including H-bonding,electrostatic, hydrophobic, coordination and metal chelating.

Some examples of F end groups capable of H-bonding include but are notlimited to modified bases adenine, thymine, guanine, cytosine, orderivatives thereof, peptides etc. Some examples of endgroups capable ofelectrostatic interactions include but are not limited to carboxylate,phosphate, sulfonate, secondary-, tertiary- and quaternary-amines. Someexamples of endgroups capable of hydrophobic interactions include butare not limited to C1-C30 aliphatic groups, benzyl and aliphatic benzylgroups, saturated and unsaturated hydrophobes. Some examples ofendgroups capable of coordination interactions include but are notlimited to metal ions and/or metal ion ligands. Some examples ofendgroups capable of metal chelating interactions include derivatives ofdiethylenetriamine-N,N,N′,N′,N″-pentaacetic acid (DTA),ethylenedinitrilotetraacetic acid (EDTA), or nitrilotriacetic acid(NTA).

In one embodiment, the star macromolecule comprises a functional group Fwhich is designed to interact with small molecule surfactant micelles.‘Interacts with’ is defined as any intermolecular force between twomolecules. These intermolecular forces include electrostatic, hydrogenbonding, hydrophobic, steric, dipole-dipole, pi-pi, or otherintermolecular forces.

Surfactants represent a class of molecules with a hydrophobic tail and ahydrophilic head. Some examples of surfactants include but are notlimited to linear alkylbenzenesulfonate salts (LAS), alkyl ether sulfatesalts (AEOS), alkylpolyglycosides (APG), alcohol ethoxylates, fatty acidglucoamides, betaines, alpha-olefinsulfonate salts, polysorbates, PEGs,alkylphenol ethoxylates, esterquats, imidizolium salts, diamidoquaternary ammonium salts, etc.

In one embodiment, the star macromolecule arms comprise a (co)polymersegment that exhibits an upper, or higher, critical solution temperature(UCST or HCST) whereby the star macromolecule is soluble in a liquid athigher temperature, say above 44° C., then at the lower use temperaturethe outer shell polymer segments become insoluble and self assemble toform a shear sensitive gel or in another embodiment the invention theouter shell of the star macromolecule arms comprise a (co)polymersegment that exhibits a lower critical solution temperature (LCST), say5° C., whereby the star macromolecule is soluble in a liquid at lowertemperature then at the use temperature the outer shell polymer segmentsbecome insoluble and self assemble to form a shear sensitive gel. In thecase of a LCST it is envisioned that a copolymer segment with an LCSTbelow 10° C., preferable below 5° C. would be optimal. A non-limitingexample would be a copolymerization of BuMA and DMAEMA and preparationof copolymers with designed LCST. A copolymer with 10% BuMA has a LCSTclose to 0° C. and one would use less BuMA or a less hydrophobic monomersuch as MMA to increase the LCST to ˜5° C. Indeed the Tg of the segmentof the star can be selected to allow dissolution of the star in roomtemperature aqueous media.

In one embodiment, a star macromolecule further comprise a personal careand cosmetics formulation and/or product. Personal care and cosmeticproducts include but are not limited to a shampoo, conditioner, hairlotion, tonic, hair spray, hair mousse, hair gel, hair dyes,moisturizer, suntan lotion, color cosmetic, body lotion, hand cream,baby skin-care product, facial cream, lipstick, mascara, blush,eyeliner, baby shampoo, baby moisturizer, baby lotion, shower gel, soap,shaving product, deodorant, bath cream, body wash, serum, cream, solid,gel, lubricant, gelly, balm, tooth paste, whitening gel, disposabletowel, disposable wipe or ointment.

In one embodiment a star macromolecule further comprise a home careformulation and/or product. Home care products include but are notlimited to a surface cleaner, window cleaner, laundry detergent, toiletcleaner, fabric cleaner, fabric softener, dish detergent, cleaningstick, stain stick, spray cleaners, sprayable formulations, lubricant,disposable towel or disposable wipe.

The polymer chains that comprise the arms are preferably provided with amolecular mass of greater than or equal to 500 which can range up to2,000,000. This numbers correspond to p1, p2, p3 in the range of 5 up to20,000 preferably in the range of 8 to 2,000.

In one example, the star macromolecules comprising segmented copolymersarms are directed at use in aqueous media. The stars comprise acrosslinked core, and arms comprising of water soluble copolymer(M2)_(p2) and a hydrophobic (co)polymer (M1)_(p1). Therefore in a in anon-limiting example the stars comprise a crosslinked core, and armscomprising an water soluble (co)polymer (e.g. poly(acrylic acid),poly(2-hydroxyethyl acrylate), poly(N-isopropylacrylamide),poly(ethylene glycol) methacrylate, quaternized poly(dimethylaminoethylmethacrylate), etc.) and a hydrophobic (co)polymer (e.g. polystyrene orsubstituted polystyrenes, poly(alkyl(meth)acrylate), etc.) or ahydrocarbon based segment. Suitable hydrocarbon based segments cancomprise low molecular weight α-olefin. Lower molecular weight α-olefinsare commercially available and higher molecular weight species can beprepared by telomerization of ethylene or ethylene propylene mixtures.[Kaneyoshi, H.; Inoue, Y.; Matyjaszewski, K. Macromolecules 2005, 38,5425-5435.]

In an embodiment, the polymer compositions can self assemble in solutionto provide a certain level of control over viscosity and consistencyfactors in many aqueous and oil based systems where control over therheology is a concern. Applications include; water- and solvent-basedcoating compositions, paints, inks, antifoaming agents, antifreezesubstances, corrosion inhibitors, detergents, oil-well drilling-fluidrheology modifiers, additives to improve water flooding during enhancedoil recovery, dental impression materials, cosmetic and personal careapplications including hair styling, hair conditioners, shampoos, bathpreparations, cosmetic creams, gels, lotions, ointments, deodorants,powders, skin cleansers, skin conditioners, skin emollients, skinmoisturizers, skin wipes, sunscreens, shaving preparations, and fabricsofteners, with the rheology modifier providing characteristics of highgel strength, highly shear thinning characteristics, forms versatile lowviscosity soluble concentrations, and synergistic interactions withadded agents to adjust their rheology profile to optimize propertiessuch as sedimentation, flow and leveling, sagging, spattering, etc.

One non-limiting field of applications that can exemplify the utility ofthe disclosed star macromolecules is cosmetic and personal carecompositions such as hair styling sprays, mousses, gels and shampoos,frequently contain resins, gums and adhesive polymers to provide avariety of benefits, for example, film-forming ability, thickening,sensory properties and hair shaping and setting. Polymers designed forrheological control, as thickening agents, in such compositionsgenerally focus on linear or graft copolymers which contain variousmonomers in an alternating, random or block configuration.

Suitable hydrophobic monomers that may be used to form an arm or segmentof an arm, such as a polymeric segment of an arm, of a starmacromolecule may include, but is not limited to methyl acrylate, ethylacrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate,2-ethylhexyl acrylate, decyl acrylate, octyl acrylate; methylmethacrylate; ethyl methacrylate; n-butyl methacrylate; iso-butylmethacrylate; t-butyl methacrylate; 2-ethylhexyl methacrylate; decylmethacrylate; methyl ethacrylate; ethyl ethacrylate; n-butylethacrylate; iso-butyl ethacrylate; t-butyl ethacrylate; 2-ethylhexylethacrylate; decyl ethacrylate; 2,3-dihydroxypropyl acrylate;2,3-dihydroxypropyl methacrylate; 2-hydroxypropyl acrylate;hydroxypropyl methacrylate; glycidyl methacrylate; glycidyl acrylate,acrylamides, styrene; styrene optionally substituted with one or moreC1-C12 straight or branched chain alkyl groups; or alkylacrylate. Forexample, the hydrophobic monomer may comprise styrene;alpha-methylstyrene; t-butylstyrene; p-methylstyrene; methylmethacrylate; or t-butyl-acrylate. For example, the hydrophobic monomermay comprise styrene. In certain embodiments, the hydrophobic monomermay comprise a protected functional group.

Suitable hydrophilic monomers that may be used to form an arm or segmentof an arm, such as a polymeric segment of an arm, of a starmacromolecule may include, but is not limited to, protected andunprotected acrylic acid, such as methacrylic acid, ethacrylic acid,methyl acrylate, ethyl acrylate, á-butyl acrylate, iso-butyl acrylate,t-butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, octyl acrylate;methyl methacrylate; ethyl methacrylate; n-butyl methacrylate; iso-butylmethacrylate; t-butyl methacrylate; 2-ethylhexyl methacrylate; decylmethacrylate; methyl ethacrylate; ethyl ethacrylate; n-butylethacrylate; iso-butyl ethacrylate; t-butyl ethacrylate; 2-ethylhexylethacrylate; decyl ethacrylate; 2,3-dihydroxypropyl acrylate;2,3-dihydroxypropyl methacrylate; 2-hydroxyethyl acrylate;2-hydroxypropyl acrylate; hydroxypropyl methacrylate; glycerylmonoacrylate; glyceryl monoethacrylate; glycidyl methacrylate; glycidylacrylate; acrylamide; methacrylamide; ethacrylamide; N-methylacrylamide; N,N-dimethyl acrylamide; N,N-dimethyl methacrylamide;N-ethyl acrylamide; N-isopropyl acrylamide; N-butyl acrylamide;N-t-butyl acrylamide; N,N-di-n-butyl acrylamide; N,N-diethylacrylamide;N-octyl acrylamide; N-octadecyl acrylamide; N,N-diethylacrylamide;N-phenyl acrylamide; N-methyl methacrylamide; N-ethyl methacrylamide;N-dodecyl methacrylamide; N,N-dimethylaminoethyl acrylamide; quaternisedN,N-dimethylaminoethyl acrylamide; N,N-dimethylaminoethylmethacrylamide; quaternised N,N-dimethylaminoethyl methacrylamide;N,N-dimethylaminoethyl acrylate; N,N-dimethylaminoethyl methacrylate;quaternised N,N-dimethyl-aminoethyl acrylate; quaternisedN,N-dimethylaminoethyl methacrylate; 2-hydroxyethyl acrylate;2-hydroxyethyl methacrylate; 2-hydroxyethyl ethacrylate; glycerylacrylate; 2-methoxyethyl acrylate; 2-methoxyethyl methacrylate;2-methoxyethyl ethacrylate; 2-ethoxyethyl acrylate; 2-ethoxyethylmethacrylate; 2-ethoxyethyl ethacrylate; maleic acid; maleic anhydrideand its half esters; fumaric acid; itaconic acid; itaconic anhydride andits half esters; crotonic acid; angelic acid; diallyldimethyl ammoniumchloride; vinyl pyrrolidone vinyl imidazole; methyl vinyl ether; methylvinyl ketone; maleimide; vinyl pyridine; vinyl pyridine-N-oxide; vinylfuran; styrene sulphonic acid and its salts; allyl alcohol; allylcitrate; allyl tartrate; vinyl acetate; vinyl alcohol; vinylcaprolactam; vinyl acetamide; or vinyl formamide. For example, thehydrophilic monomer may comprise protected and unprotected acrylic acid,such as methacrylic acid, ethacrylic acid, methyl acrylate, ethylacrylate, á-butyl acrylate, iso-butyl acrylate, t-butyl acrylate,2-ethylhexyl acrylate, decyl acrylate, octyl acrylate; methyl acrylate;methyl methacrylate; methyl ethacrylate; ethyl acrylate; ethylmethacrylate; ethyl ethacrylate; n-butyl acrylate; n-butyl methacrylate;n-butyl ethacrylate; 2-ethylhexyl acrylate; 2-ethylhexyl methacrylate;2-ethylhexyl ethacrylate; N-octyl acrylamide; 2-methoxyethyl acrylate;2-hydroxyethyl acrylate; N,N-dimethylaminoethyl acrylate;N,N-dimethylaminoethyl methacrylate; acrylic acid; methacrylic acid;N-t-butylacrylamide; N-sec-butylacrylamide; N,N-dimethylacrylamide;N,N-dibutylacrylamide; N,N-dihydroxyethyllacrylamide; 2-hydroxyethylacrylate; 2-hydroxyethyl methacrylate; benzyl acrylate;4-butoxycarbonylphenyl acrylate; butyl acrylate; 4-cyanobutyl acrylate;cyclohexyl acrylate; dodecyl acrylate; 2-ethylhexyl acrylate; heptylacrylate; iso-butyl acrylate; 3-methoxybutyl acrylate; 3-methoxypropylacrylate; methyl acrylate; N-butyl acrylamide; N,N-dibutyl acrylamide;ethyl acrylate; methoxyethyl acrylate; hydroxyethyl acrylate; ordiethyleneglycolethyl acrylate. For example, the hydrophilic monomer maycomprise protected and unprotected acrylic acid, such as methacrylicacid, ethacrylic acid, methyl acrylate, ethyl acrylate, α-butylacrylate, iso-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate,decyl acrylate, octyl acrylate; 2-hydroxyethyl acrylate;N-isopropylacrylamide; ethylene glycol methacrylate; (polyethyleneglycol) methacrylate; or quaternized dimethylaminoethyl methacrylate.For example, the hydrophilic monomer may comprise acrylic acid,methacrylic acid, 2-hydroxyethyl acrylate, acrylamide, vinylpyrrolidone, vinyl pyridine, styrene sulphonic acid, PEG-methacrylate,2-(dimethylamino)ethyl methacrylate, 2-(trimethylamino)ethylmethacrylate, 2-acrylamido-2-methylpropane sulphonic acid. For example,the hydrophilic monomer may comprise acrylic acid.

Suitable monomers that may be used to form a core of a starmacromolecule may include, but are not limited to, a multifunctionalmonomer, for example, a hexafunctional monomer, a pentafunctionalmonomer, a tetrafunctional monomer, a trifunctional monomer, or adifunctional monomer. For example, a crosslinker may be a hydrophobicmonomer or a hydrophilic monomer, such as a hydrophobic multifunctionalmonomer or a hydrophilic multifunctional monomer, for example, ahydrophobic difunctional monomer or a hydrophilic difunctional monomer.For example, the crosslinker may be a hydrophobic crosslinker,including, but not limited to, 1,2-divinylbenzene; 1,3-divinylbenzene;1,4-divinylbenzene; 1,2-ethanediol di(meth)acrylate; 1,3-propanedioldi(meth)acrylate; 1,4butanediol di(meth)acrylate; 1,5-hexanedioldi(meth)acrylate; divinylbenzene; ethyleneglycol di(meth)acrylate;di(ethylene glycol)diacrylate (DEGlyDA); propyleneglycoldi(meth)acrylate; butyleneglycol di(meth)acrylate; triethyleneglycoldi(meth)acrylate; polyethyleneglycol di(meth)acrylate;polypropyleneglycol di(meth)acrylate; polybutyleneglycoldi(meth)acrylate; allyl(meth)acrylate; glycerol di(meth)acrylate;trimethylolpropane tri(meth)acrylate; pentaerythritoltetra(meth)acrylate; allyl methacrylate; or allyl acrylate. For example,the crosslinker may be di(ethylene glycol)diacrylate (DEGlyDA) ordivinylbenzene. For example, the crosslinker may be divinylbenzene.

Suitable star macromolecules may include, but are not limited to, amikto star macromolecule, a water-soluble star macromolecule, agel-forming star macromolecule, emulsifier/thickening agent starmacromolecules or combinations thereof. In certain embodiments, the starmacromolecule may have a molecular weight of greater than 100,000 g/mol,for example, between 100,000 g/mol and 2,000,000 g/mol, such as between125,000 g/mol and 1,750,000 g/mol; between 150,000 g/mol and 1,750,000g/mol; between 200,000 g/mol and 1,500,000 g/mol; between 225,000 g/moland 1,250,000 g/mol; between 125,000 g/mol and 1,000,000 g/mol; between125,000 g/mol and 900,000 g/mol; between 125,000 g/mol and 800,000g/mol; between 125,000 g/mol and 700,000 g/mol; between 150,000 g/moland 650,000 g/mol; between 200,000 g/mol and 600,000 g/mol; between225,000 g/mol and 650,000 g/mol; between 250,000 g/mol and 550,000g/mol; between 350,000 g/mol and 500,000 g/mol; between 300,000 g/moland 500,000 g/mol; or between 350,000 g/mol and 750,000 g/mol.

Suitable star macromolecules may have a polydispersity index (PDI) ofless than 2.5, for example, a PDI of less that 2.0, such as less than1.7. For example, a star macromolecule may have a PDI of between 1.0 to2.5, such as between 1.0 and 2.3; between 1.0 and 2.0; between 1.0 and1.9; between 1.0 and 1.8; between 1.0 and 1.7; between 1.0 and 1.6;between 1.0 and 1.5; between 1.0 and 1.4; between 1.0 and 1.3; between1.0 and 1.2; between 1.0 and 1.1; between 1.05 and 1.75; between 1.1 and1.7; between 1.15 and 1.65; or between 1.15 and 1.55.

Suitable star macromolecules may comprise arms that are of the same typeor a different type and are homopolymeric, copolymeric, comprisemultiple block segment, random segments, gradient segments and or noparticular segments. In certain embodiments, the star macromolecule maycomprise, for example, one or more arm-types, such as, two or more,three or more, four or more, or five or more arm-types. Suitable armtypes may include, but are not limited to, homopolymeric arms,copolymeric arms, such as random copolymeric arms or block copolymericarms, or combinations thereof. For example, a star macromolecule maycomprise homopolymeric arms and copolymeric arms, such as blockcopolymeric arms. Suitable arm types may also include, but are notlimited to, hydrophilic arms, hydrophobic arms, or amphiphilic arms. Incertain embodiments, a star macromolecule arm may comprise hydrophilicpolymeric segments comprising hydrophilic monomeric residues,hydrophobic polymeric segments comprising hydrophobic monomericresidues, amphiphilic polymeric segments comprising amphiphilicmonomeric residues, or combinations thereof. For example, in certainembodiments, a star macromolecule may comprise homopolymeric arms andcopolymeric arms, such as hydrophilic homopolymeric arms and copolymericarms comprising hydrophilic polymeric segments and hydrophobic polymericsegments.

Suitable star macromolecules may also comprise arms that are covalentlylinked to the core of the star macromolecule. In certain embodiments,the arms of a star macromolecule may be covalently linked to the core ofthe star macromolecule via crosslinking, such as crosslinking with acrosslinker, for example, a hydrophobic difunctional crosslinker or ahydrophilic difunctional crosslinker. For example, arms of a starmacromolecule, such as homopolymeric arms and block copolymeric arms ofa mikto star macromolecule, may be covalently linked together to form acore by crosslinking an end of the arms with a crosslinker, such as witha hydrophobic difunctional crosslinker or a hydrophilic difunctionalcrosslinker.

Suitable star macromolecules may also comprise arms of varying lengthand/or degree of polymerization. In certain embodiments, for example, astar macromolecule may comprise homopolymeric arms and block copolymericarms, wherein the homopolymeric arms of a shorter length and/or a lesserdegree of polymerization in relation to the block copolymeric arms. Incertain embodiments, for example, a star macromolecule may comprisehomopolymeric arms and block copolymeric arms, wherein the blockcopolymeric arms of a longer length and/or a greater degree ofpolymerization in relation to the homopolymeric arms. In certainembodiments, a star macromolecule may comprise hydrophilic homopolymericarms and block copolymeric arms, comprising hydrophobic polymericsegments distal to the star core and hydrophilic polymeric segments thatare proximal to the core of the star, wherein a distal portion of thehydrophilic polymeric segments of the copolymeric arm extends beyond adistal portion of the hydrophilic homopolymeric arms. For example, astar macromolecule may comprise hydrophilic homopolymeric armscomprising polymerized hydrophilic monomeric residues and blockcopolymeric arms comprising hydrophobic polymeric segments distal to thecore of the star and hydrophilic polymeric segments that are proximal tothe core of the star, wherein the distal hydrophobic polymeric segmentsextend beyond the most distal portion, in relation to the core, of thehydrophilic homopolymeric arms, and/or wherein a distal portion of theproximal hydrophilic polymeric segments of the copolymeric arm extendbeyond the most distal portion, in relation to the core, of thehydrophilic homopolymeric arms. In certain embodiments, a starmacromolecule may comprise hydrophilic homopolymeric arms and blockcopolymeric arms, comprising hydrophobic polymeric segments distal tothe star core and hydrophilic polymeric segments that are proximal tothe star core, wherein the degree of polymerization of the hydrophilicpolymeric segments of the copolymeric arm is greater than, for example,20% greater than, such as between 30% to 300% greater than, between 40%to 250%, between 50% to 200%, or between 75% to 250% greater than, thedegree of polymerization of the hydrophilic homopolymeric arms, suchthat a distal portion of the hydrophilic polymeric segments of thecopolymeric arm extends beyond the a distal portion of the hydrophilichomopolymeric arms.

In certain embodiments, a star macromolecule may comprise hydrophilichomopolymeric arms comprising polymerized hydrophilic monomeric residuesand block copolymeric arms comprising hydrophobic polymeric segmentsdistal to the core of the star and hydrophilic polymeric segmentsproximal to the core of the star, wherein the polymerized hydrophilicmonomeric residues of the homopolymeric arm and the hydrophilicpolymeric segments of the copolymeric arm may be derived from the samehydrophilic monomers, and may have the same or different degree ofpolymerization, for example, a degree of polymerization of between 50 to500 monomeric residues, such as, between 50 to 400 monomeric residues;between 50 to 300 monomeric residues; between 50 to 200 monomericresidues; between 100 to 250 monomeric residues; between 125 to 175monomeric residues; or between 150 to 300 monomeric residues. Forexample, a star macromolecule may comprise hydrophilic homopolymericarms comprising polymerized hydrophilic monomeric residues and blockcopolymeric arms comprising hydrophobic polymeric segments distal to thecore of the star and hydrophilic polymeric segments proximal to the coreof the star, wherein the polymerized hydrophilic monomeric residues ofthe homopolymeric arm and the hydrophilic polymeric segments of thecopolymeric arm may be derived from the same hydrophilic monomers, andmay have the same degree of polymerization, and wherein the hydrophibicpolymeric segments of the copolymeric arm may have a degree ofpolymerization of between 1 to 60 monomeric residues, such as between 1to 50 monomeric residues; between 1 to 45 monomeric residues; between 5to 40 monomeric residues; between 8 to 35 monomeric residues; between 10to 30 monomeric residues; between 12 to 25 monomeric residues; between14 to 20 monomeric residues; between 15 to 30 monomeric residues; orbetween 5 to 20 monomeric residues.

Suitable star macromolecules may have a wide range of total number ofarms, for example, a star macromolecule may comprise greater than 15arms. For example, a suitable star macromolecule may comprise between 15and 100 arms, such as between 15 and 90 arms; between 15 and 80 arms;between 15 and 70 arms; between 15 and 60 arms; between 15 and 50 arms;between 20 and 50 arms; between 25 and 45 arms; between 25 and 35 arms;between 30 and 45 arms; or between 30 and 50 arms.

Suitable star macromolecules may have more than one arm type, such astwo or more different arm types, where in a molar ratio of the differentarm types may be between 20:1 and 1:1. For example, a star macromoleculecomprising two different arm types, such as a homopolymeric arm, forexample, a hydrophilic homopolymeric arm, and a copolymeric arm, forexample, a copolymeric arm comprising hydrophilic polymeric segments andhydrophobic polymeric segments, may have a molar ratio of the twodifferent arm types between 20:1 to 2:1, such as between 15:1 to 2:1;between 10:1 to 2:1; between 9:1 to 2:1; between 8:1 to 2:1; between 7:1to 2:1; between 6:1 to 2:1; between 5:1 to 2:1; between 4:1 to 2:1;between 3:1 to 2:1; between 2:1 to 1:1; between 8:1 to 3:1; between 7:1to 2:1; or between 5:1 to 3:1.

Suitable star macromolecules may include, but is not limited to,comprising arms having a molecular weight of greater than 10,000 g/mol.For example, a star macromolecule may comprise arms having a molecularweight of between 10,000 g/mol and 200,000 g/mol, such as between 10,000g/mol and 175,000 g/mol; between 10,000 g/mol and 150,000 g/mol; between10,000 g/mol and 125,000 g/mol; between 10,000 g/mol and 100,000 g/mol;between 10,000 g/mol and 90,000 g/mol; between 10,000 g/mol and 80,000g/mol; between 10,000 g/mol and 70,000 g/mol; between 60,000 g/mol and50,000 g/mol; between 10,000 g/mol and 40,000 g/mol; between 10,000g/mol and 30,000 g/mol; between 10,000 g/mol and 20,000 g/mol; between20,000 g/mol and 175,000 g/mol; between 20,000 g/mol and 100,000 g/mol;between 20,000 g/mol and 75,000 g/mol; between 20,000 g/mol and 50,000g/mol; between 15,000 g/mol and 45,000 g/mol; or between 15,000 g/moland 30,000 g/mol.

Suitable arms of a star macromolecule may include, but is not limitedto, arms having an HLB value of at least 17 (wherein the HLB iscalculated per the formula set forth in the test procedures). Forexample, suitable arms of a star macromolecule may have an HLB value ofgreater than 17.25, such as greater than 18.5; at least 19; between 17.5to 20; between 17.5 to 19.5; between 18 to 20; between 18.5 to 20;between 19 to 20; between 19.5 to 20; between 18 to 19.5; between 18.5to 19.75; between 18.2 to 19.2; or between 18.75 to 19.5.

Suitable hydrophobic polymeric segments of a copolymeric arm of a starmacromolecule may include, but is not limited to, hydrophobic polymericsegments having an HLB value of less than 8. For example, suitablehydrophobic polymeric segments may have an HLB value of less than 7,such as less than 6; less than 5; less than 4; less than 3; less than 2;or about 1.

Suitable arms of a star macromolecule may include, but is not limitedto, arms having a polydispersity index (PDI) value of less than 2.5. Forexample, suitable arms of a star macromolecule may have PDI value ofless than 2.25, such as less that 2.0; less than 1.7; between 1.0 to2.5, such as between 1.0 and 2.3; between 1.0 and 2.0; between 1.0 and1.9; between 1.0 and 1.8; between 1.0 and 1.7; between 1.0 and 1.6;between 1.0 and 1.5; between 1.0 and 1.4; between 1.0 and 1.3; between1.0 and 1.2; between 1.0 and 1.1; between 1.05 and 1.75; between 1.1 and1.7; between 1.15 and 1.65; or between 1.15 and 1.55.

Suitable cores of a star macromolecule may be formed by or derived from,but is not limited to, crosslinking of a plurality of arms and acrosslinker. For example, a core may be formed by or derived fromcrosslinking of a plurality of homopolymeric arms and a plurality ofcopolymeric arms with a crosslinker, such as a mutlifunctional monomercrosslinker, for example, a hydrophobic difunctional monomercrosslinker. In certain embodiments, the core may be formed or derivedfrom crosslinking a plurality of hydrophilic homopolymeric arms and aplurality of copolymeric arms, comprising block hydrophilic polymericsegments and block hydrophobic polymeric segments, with a crosslinker,such as a hydrophobic difunctional monomer crosslinker, for exampledivinylbenzene, wherein the molar ratio of the homopolymeric arms to thecopolymeric arms may be between 20:1 to 2:1.

Suitable star macromolecules may include, but is not limited to,comprising a core having a molecular weight of greater than 3,000 g/mol.For example, a star macromolecule may comprise a core having a molecularweight of between 3,000 g/mol and 50,000 g/mol, such as between 3,000g/mol and 45,000 g/mol; between 3,000 g/mol and 40,000 g/mol; between3,000 g/mol and 30,000 g/mol; between 3,000 g/mol and 20,000 g/mol;between 3,000 g/mol and 15,000 g/mol; between 5,000 g/mol and 40,000g/mol; between 6,000 g/mol and 30,000 g/mol; between 7,000 g/mol and25,000 g/mol; between 8,000 g/mol and 20,000 g/mol; between 5,000 g/moland 15,000 g/mol; between 7,000 g/mol and 12,000 g/mol; between 5,000g/mol and 9,000 g/mol; between 8,000 g/mol and 10,000 g/mol; or between9,000 g/mol and 15,000 g/mol.

Suitable star macromolecules may be used to form a clear, homogeneousgel when dissolved in water at a concentration of at least 0.05 wt. % ata pH of about 7.5 at STP. For example, a star macromolecule may form aclear, homogeneous gel when dissolved in water at a concentration ofbetween 0.05 wt. % to 3 wt. %, such as between 0.1 wt. % to 2.5 wt. %;between 0.1 wt. % to 2 wt. %; between 0.2 wt. % to 2.0 wt. %; between0.2 wt. % to 1.5 wt. %; between 0.2 wt. % to 1.0 wt. %; between 0.2 wt.% to 2.5 wt. %; between 0.3 wt. % to 2.5 wt. %; between 0.4 wt. % to 2.0wt. %; between 0.5 wt. % to 2.0 wt. %; between 0.6 wt. % to 2.0 wt. %;between 0.7 wt. % to 1.5 wt. %; between 0.8 wt. % to 1.2 wt. %; between0.9 wt. % to 1.1 wt. %; between 0.5 wt. % to 2.5 wt. %; between 0.75 wt.% to 1.5 wt. %; or between 0.8 wt. % to 1.6 wt. %.

Suitable star macromolecules, in accordance with the pH Efficiency RangeTest Procedure described below herein, may be used to form a clear,homogeneous gel, wherein the star macromolecule at a concentration of0.4 wt. %, may have a viscosity of at least 20,000 cP, at a pH ofbetween about 4 to about 12, for example, at a pH of between about 5 toabout 11.5 such as at a pH of between about 5 to about 11; between about5 to about 10.5; between about 5 to about 10; between about 5 to about9.5; between about 5 to about 9; between about 5 to about 8.5; betweenabout 5 to about 8; between about 6 to about 11; between about 5.5 toabout 10; between about 6 to about 9; between about 6.5 to about 8.5;between about 7 to about 8; between about 7.5 to about 8.5; or betweenabout 6.5 to about 7.5.

In certain embodiments, for example, suitable star macromolecules, inaccordance with the pH Efficiency Range Test Procedure described belowherein, may be used to form a clear, homogeneous gel, wherein the starmacromolecule at a concentration of 0.4 wt. %, may have a viscosity ofat least 20,000 cP at a pH between about 5.5 to about 11. For example,at a pH between about 5.5 to about 11 may have a viscosity of at least30,000 cP, such as, at least 40,000 cP; between 20,000 cP to 250,000 cP;between 20,000 cP to 250,000 cP; between 20,000 cP to 225,000 cP;between 20,000 cP to 200,000 cP; between 20,000 cP to 175,000 cP;between 20,000 cP to 150,000 cP; between 20,000 cP to 125,000 cP;between 30,000 cP to 250,000 cP; between 30,000 cP to 200,000 cP;between 40,000 cP to 175,000 cP; or between 40,000 cP to 150,000 cP. Forexample, a gel at a pH between about 6 to about 11 may have a viscosityof at least 20,000 cP, such as, at least 30,000 cP; at least 40,000 cP;between 20,000 cP to 250,000 cP; between 20,000 cP to 250,000 cP;between 20,000 cP to 225,000 cP; between 20,000 cP to 200,000 cP;between 20,000 cP to 175,000 cP; between 20,000 cP to 150,000 cP;between 20,000 cP to 125,000 cP; between 30,000 cP to 250,000 cP;between 30,000 cP to 200,000 cP; between 40,000 cP to 175,000 cP; orbetween 40,000 cP to 150,000 cP. For example, at a pH between about 7 toabout 10.5 may have a viscosity of at least 60,000 cP, such as at least70,000 cP; between 60,000 cP to 250,000 cP; between 60,000 cP to 225,000cP; between 60,000 cP to 200,000 cP; between 60,000 cP to 175,000 cP;between 60,000 cP to 150,000 cP; between 60,000 cP to 125,000 cP;between 60,000 cP to 115,000 cP; between 60,000 cP to 105,000 cP; orbetween 60,000 cP to 100,000 cP. For example, at a pH between about 7.5to about 9.0 may have a viscosity of at least 95,000 cP, such as atleast 100,000 cP; between 95,000 cP to 250,000 cP; between 95,000 cP to225,000 cP; between 95,000 cP to 200,000 cP; between 95,000 cP to175,000 cP; between 95,000 cP to 150,000 cP; between 95,000 cP to125,000 cP; between 95,000 cP to 115,000 cP; or between 95,000 cP to105,000 cP.

Suitable star macromolecules, in accordance with the Dynamic Viscosity &Shear-Thinning Test Procedure described below herein, may be used toform a clear, homogeneous gel, wherein the star macromolecule at aconcentration of 0.4 wt. %, may have a viscosity of less than 5,000 cPat a shear rate of 4 sec⁻¹, such as a viscosity of less than 4,000 cP.For example, the star macromolecule at a concentration of 0.4 wt. %, mayhave a viscosity have a viscosity of less than 5,000 cP at a shear rateof 6 sec⁻¹, such as a viscosity of less than 4,000 cP or less than 3,000cP. For example, a gel may have a viscosity of less than 15,000 cP at ashear rate of 0.7 sec⁻¹, such as a viscosity of less than 14,000 cP orless than 13,000 cP. Suitable gels may include, but is not limited to,gels having shear-thinning value of at least 5, such as a shear-thinningvalue of at least 6, or between 5 to 15, such as between 5 to 15;between 7 to 12; between 8 to 10; or between 6 to 13.

Suitable star macromolecules, in accordance with the Dynamic Viscosity &Shear-Thinning Test Procedure described below herein, include those thathave a shear-thinning value of at least 15, such as a shear-thinningvalue of between 15 to 100, such as between 15 to 90; between 20 to 80;between 25 to 70; between 25 to 50; or between 30 to 40.

Suitable star macromolecules, in accordance with the Salt-Induced BreakTest Procedure described below herein, include those that have asalt-induced break value of at least 50%, such as a salt-induced breakvalue of between 65% to 100%, such as between 75% to 100%; between 80%to 95%; between 75% to 90%; between 50% to 85%; between 70% to 95%; orbetween 60% to 100%.

Suitable star macromolecules, in accordance with the pH Efficiency RangeTest Procedure described below herein, include those that have apH-induced break value of at least 15%, such as a pH-induced break valueof between 15% to 100%, such as between 25% to 100%; between 30% to 95%;between 40% to 90%; between 50% to 85%; between 70% to 95%; between 80%to 97%; between 90% to 99%; between 95% to 100%; or between 60% to 100%.

Suitable star macromolecules, in accordance with the Dynamic Viscosity &Shear-Thinning Test Procedure described below herein, include those thathave a dynamic viscosity value, of greater than 20,000 cP at 1 rpm, andat a concentration of 0.2 wt. %, such as a dynamic viscosity value ofgreater than 24,000 cP; greater than 28,000 cP; or greater than 30,000cP at a concentration of 0.2 wt. %.

Suitable emulsions may include, but is not limited to, emulsions thatare emulsifier-free and wherein the emulsion is thickened by a starmacromolecule. For example, the star macromolecule that may be includedin the emulsifier-free emulsion may be a water-soluble starmacromolecule, wherein the water-soluble star macromolecule emulsifiesthe emulsifier-free emulsion.

Suitable star macromolecules, include star macromolecules that have anemulsion value of greater than 60 minutes, for example, greater than 3hours, such as greater than 6 hours; greater than 10 hours; greater than20 hours; greater than 40 hours; or greater than 100 hours.

Suitable star macromolecules, according to Formula X, may include starmacromolecules wherein P1, P2, and/or P3 comprise hydrophobic monomers,hydrophilic monomers, amphiphilic monomers, or combinations thereof. Forexample, P1 comprises hydrophobic monomers, P2 comprises hydrophilicmonomers, and P3 comprises hydrophilic monomers. For example, starmacromolecules, according to Formula X, may include star macromoleculeswherein q1 may have a value of between 1 to 100, for example, between 1to 60, such as, between 1 to 45; between 5 to 40; between 8 to 35;between 10 to 30; between 12 to 25; between 14 to 20; between 15 to 30;or between 5 to 20; and q2 and/or q3 have a value of between 50 to 500,for example, between 50 to 400, such as, between 50 to 300; between 50to 200; between 100 to 250; between 125 to 175; or between 150 to 300.For example, star macromolecules, according to Formula X, may includestar macromolecules wherein r or t, or the sum of r and t, may begreater than 15, such as between 15 and 100; between 15 and 90; between15 and 80; between 15 and 70; between 15 and 60; between 15 and 50;between 20 and 50; between 25 and 45; between 25 and 35; between 30 and45; or between 30 and 50. For example, star macromolecules, according toFormula X, may include star macromolecules wherein the molar ratio of rto t is in the range of between 20:1 to 2:1, such as between 15:1 to2:1; between 10:1 to 2:1; between 9:1 to 2:1; between 8:1 to 2:1;between 7:1 to 2:1; between 6:1 to 2:1; between 5:1 to 2:1; between 4:1to 2:1; between 3:1 to 2:1; between 2:1 to 1:1; between 8:1 to 3:1;between 7:1 to 2:1; or between 5:1 to 3:1. For example, starmacromolecules, according to Formula X, may include star macromoleculeswherein the core may be derived from crosslinker monomers, such ashydrophobic crosslinker monomers. For example, star macromolecules,according to Formula X, may include star macromolecules wherein the coremay comprise crosslinker monomeric residues, such as hydrophobiccrosslinker monomeric residues. For example, star macromolecules,according to Formula X, may include star macromolecules wherein the arm[(P1)_(q1)-(P2)_(q2)]_(t) may be homopolymeric or copolymeric, such asblock copolymeric.

Suitable star macromolecules, may include, but is not limited to, starmacromolecules formed by crosslinking the arms with a crosslinker, suchas crosslinking homopolymeric arms and block copolymeric arms with ahydrophobic crosslinker. For example, the homopolymeric arms and thecopolymeric arms of a star macromolecule may be covalently attached tothe core via crosslinkage with a crosslinker. For example, a core of aprepared star macromolecule may be prepared by crosslinking an end of ahomopolymeric arm with an end of a copolymeric arm, such as an end of ahydrophilic homopolymeric arm with a hydrophilic end of a copolymericarm. For example, the core of a prepared star macromolecules may beformed by crosslinking an ATRP-functional terminal group end of ahomopolymeric arm with an ATRP-functional terminal group end of acopolymeric arm.

Suitable initiators that may be used to form the star macromoleculesdisclosed herein, may include, but is not limited to, nitroxideinitiators, such as stable nitroxide initiators, for example,2,2,6,6-Tetramethylpiperidine-1-oxyl, sometimes called TEMPO; transitionmetal complexes, such cobalt containing complexes; ATRP initiators,comprising halides, such as, bromide, chloride, or iodide, andtransition metal sources, such as, copper, iron, ruthenium transitionmetal sources; iodide with RCTP catalysts, such as germanium or tincatalysts; RAFT initiators, such as dithioesters, dithiocarbamates, orxanthates; ITP catalysts, comprising iodides; tellurium compounds (e.g.,TERP); stibine compounds (e.g., SBRP); or bismuth compounds (e.g.,BIRP). For example, in certain embodiments, an initiator may furthercomprise a monomeric residue, a polymeric segment comprising monomericresidues, or a small-molecule. For example, in certain embodiments, aninitiator may comprise an ATRP initiator, wherein the ATRP initiatorserves as a terminal functional group. For example, in certainembodiments, an initiator may comprise an ATRP-functional terminalgroup, comprising an ATRP initiator, such as halides and transitionmetal sources.

Suitable materials comprising the star macromolecules disclosed herein,include, but is not limited to, lotions, such as cosmetic lotions,personal care lotions, body lotions, emulsifier-free body lotions;serums, such as anti-aging serums; sunscreens, such as SPF 30sunscreens, SPF 35 sunscreens, SPF 40 sunscreens, SPF 50 sunscreens;creams, such as face-creams, cosmetic creams; hair products, such asshampoos, hair styling products, hair sprays, mousses, hair gels, hairconditioners, bath preparations; gels, such as cosmetic gels or personalcare gels; skin application products, such as ointments, deodorants,personal care powders, skin cleansers, skin conditioners, skinemollients, skin moisturizers, skin wipes, shaving preparations; fabricsofteners; dental impression materials; or variations thereof.

Suitable materials comprising an emulsifier-free emulsion, wherein theemulsion is thickened by a star macromolecule disclosed herein, mayinclude, but is not limited to, lotions, such as cosmetic lotions,personal care lotions, body lotions, emulsifier-free body lotions;serums, such as anti-aging serums; sunscreens, such as SPF 30sunscreens, SPF 35 sunscreens, SPF 40 sunscreens, SPF 50 sunscreens;creams, such as face-creams, cosmetic creams; hair products, such asshampoos, hair styling products, hair sprays, mousses, hair gels, hairconditioners, bath preparations; gels, such as cosmetic gels or personalcare gels; skin application products, such as ointments, deodorants,personal care powders, skin cleansers, skin conditioners, skinemollients, skin moisturizers, skin wipes, shaving preparations; fabricsofteners; dental impression materials; or variations thereof.

In an embodiment, examples of suitable lotion formulations include bodylotion formulations, comprising an emulsifier-free emulsion, wherein theemulsion is thickened by a star macromolecule disclosed herein, mayinclude, but is not limited to, formulations comprising one or more ofthe following: Deionized Water; Disodium EDTA; 1,3-Butylene Glycol;Glycerin; Allantoin; Urea; TEA 99%; Edible Olive Oil (N.F.); SheaButter; Wickenol 171; Squalane; Crodamol CAP; Crodamol STS; Crodacol C;Tween 20; Lipo GMS 470; PEG 100 Stearate; Cetyl Palmitate; CrodamolPTIS; Crodafos CES; DC 1401; Evening Primrose Oil; Vitamin E Acetate;D-Panthenol; Distinctive HA2; Diocide; or derivatives or combinationsthereof.

In an embodiment, examples of suitable lotion formulations includeemulsifier-free personal care lotion formulations, comprising anemulsifier-free emulsion, wherein the emulsion is thickened by a starmacromolecule disclosed herein, may include, but is not limited to,formulations comprising one or more of the following: Deionized Water;Disodium EDTA; 1,3-Butylene Glycol; Glycerin; Allantoin; Urea; TEA 99%;Edible Olive Oil (N.F.); Wickenol 171; Myritol 318; Squalane; CrodamolPTIS; Isododecane; Evening Primrose Oil; Vitamin E Acetate; D-Panthenol;Distinctive HA2; Diocide; or derivatives or combinations thereof.

In an embodiment, examples of suitable formulations include serumformulations, such as anti-aging serum formulations, comprising anemulsifier-free emulsion, wherein the emulsion is thickened by a starmacromolecule disclosed herein, may include, but is not limited to,formulations comprising one or more of the following: Deionized Water;Disodium EDTA; Glycerin; 1,3-Butylene Glycol; Caffeine; Allantoin;Triethanolamine 99%; Crodamol STS; Myritol 318; Wickenol 171; Tween 20;Crodaphos CES; BVOSC; Vitamin E Acetate; Vitamin A Palmitate; VitaminD3; Gransil IDS; D-Panthenol; DC Upregulex; DC Skin Bright MG; Actiphyteof Japanese Green Tea G; Actiphyte of Grape Seed G; DC Hydroglide;Diocide; or derivatives or combinations thereof.

In an embodiment, suitable formulations include sunscreen formulations,comprising an emulsifier-free emulsion, wherein the emulsion isthickened by a star macromolecule disclosed herein, may include, but isnot limited to, formulations comprising one or more of the following:Deionized Water; Disodium EDTA; Glycerin; Triethanolamine 99%;Homomethyl Salicylate; Ethylhexyl Salicylate; Avobenzone; Benzophenone3; Myritol 318; Lexfeel 7; Octocrylene; Cetyl Alcohol; PEG-15 Cocamine;Lipo GMS 470; Crodafos CS-20; Vitamin E Acetate; Aloe Vera Leaf Juice;Diocide; or derivatives or combinations thereof.

In an embodiment, examples of suitable formulations include face creamformulations, comprising an emulsifier-free emulsion, wherein theemulsion is thickened by a star macromolecule disclosed herein, mayinclude, but is not limited to, formulations comprising one or more ofthe following: Deionized Water; Disodium EDTA; 1,3 Butylene Glycol;Glycerin; Caffeine; Allantoin; Triethanolamine 99%; Myritol 318; OctylPalmitate; Wickenol 171; Crodaphos CES; Cetyl Alcohol; Pationic SSL;Cetyl Palmitate; Vitamin E Acetate; BVOSC; Lexfeel 7; Lipo GMS 470;Vitamin A/D3 in Corn Oil; DC 1401; Actiphyte of Japanese Green Tea G;Actiphyte of Grape Seed G; DC Hydroglide; Diocide; or derivatives orcombinations thereof.

Synthesis of the Rheology Modifier

Although any conventional method can be used for the synthesis of themulti-arm star macromolecules of the invention, free radicalpolymerization is the preferred and living/controlled radicalpolymerization (CRP) is the most preferred process.

CRP has emerged during the past decade as one of the most robust andpowerful techniques for polymer synthesis, as it combines some of thedesirable attributes of conventional free radical polymerization (e.g.,the ability to polymerize a wide range of monomers, tolerance of variousfunctionality in monomer and solvent, compatibility with simpleindustrially viable reaction conditions) with the advantages of livingionic polymerization techniques (e.g., preparation of low polydispersityindex (PDI=M_(w)/M_(n)) polymer and chain-end functionalized homo- andblock (co)polymers). The basic concept behind the various CRP proceduresis the reversible activation of a dormant species to form thepropagating radical. A dynamic and rapid equilibrium between the dormantand the active species minimizes the probability of bimolecular radicaltermination reactions and provides an equal opportunity for propagationto all polymer (or dormant) chains.

CRP procedures can be classified into three main groups based on themechanism of reversible activation: (a) stable free radicalpolymerization (SFRP, Scheme 1a), (b) degenerative chain transferpolymerization (DT, Scheme 1b), and (c) atom transfer radicalpolymerization (ATRP, Scheme 1c).

As shown in Scheme 1 various capping agents, X, are used for thedifferent CRP procedures and they are summarized in Scheme 2. Theyinclude stable nitroxides (Scheme 2a), transition metal complexes(Scheme 2b), halides with transition metal catalysts (Scheme 2c), iodinewith catalysts (Scheme 2d), sulfur compounds (Scheme 2e), iodine (Scheme20, and organometal compounds (Scheme 2g).

Star polymers are nano-scale materials with a globular shape. Asillustrated in FIG. 1, stars formed by the “arm first” procedure,discussed in detail below, can have a crosslinked core and canoptionally possess multiple segmented arms of similar composition. Starscan be designed as homo-arm stars or mikto-arm stars. FIG. 1A representsa homo-arm star with block copolymer arms. Mikto-arm stars have armswith different composition or different molecular weight; FIGS. 1B and1C. Both homo-arm stars and mikto-arm stars can optionally possess ahigh-density of peripheral functionality.

Synthesis of star polymers of the invention can be accomplished by“living” polymerization techniques via one of three strategies: 1)core-first” which is accomplished by growing arms from a multifunctionalinitiator; 2) “coupling-onto” involving attaching preformed arms onto amultifunctional core and the 3) arm-first” method which involvescross-linking preformed linear arm precursors using a divinyl compound

While all above controlled polymerization procedures are suitable forpreparation of an embodiment of the disclosed self assembling starmacromolecules. Other embodiments are also exemplified, for example, thepreparation of the self assembling multi-arm stars with narrow MWD, incontrast to prior art using ATRP. The reason for the use of theControlled Radical Polymerization process (CRP) known as ATRP; disclosedin U.S. Pat. Nos. 5,763,546; 5,807,937; 5,789,487; 5,945,491; 6,111,022;6,121,371; 6,124,411; 6,162,882; and U.S. patent application Ser. Nos.09/034,187; 09/018,554; 09/359,359; 09/359,591; 09/369,157; 09/126,768and 09/534,827, and discussed in numerous publications listed elsewherewith Matyjaszewski as co-author, which are hereby incorporated into thisapplication, is that convenient procedures were described for thepreparation of polymers displaying control over the polymer molecularweight, molecular weight distribution, composition, architecture,functionality and the preparation of molecular composites and tetheredpolymeric structures comprising radically (co)polymerizable monomers,and the preparation of controllable macromolecular structures under mildreaction conditions.

An aspect of the present invention relates to the preparation and use ofmulti-arm star macromolecules by an “arm first” approach, discussed byGao, H.; Matyjaszewski, K. JACS; 2007, 129, 11828. The paper and citedreferences therein are hereby incorporated by reference to describe thefundamentals of the synthetic procedure. The supplemental informationavailable within the cited reference provides a procedure forcalculation of the number of arms in the formed star macromolecule.

It is expected that biphasic systems such as a miniemulsion or an abinitio emulsion system would also be suitable for this procedure sinceminiemulsion systems have been shown to function as dispersed bulkreactors [Min, K.; Gao, H.; Matyjaszewski, K. Journal of the AmericanChemical Society 2005, 127, 3825-3830] with the added advantage ofminimizing core-core coupling reactions based on compartmentalizationconsiderations.

In one embodiment star macromolecules are prepared with composition andmolecular weight of each segment predetermined to perform as rheologymodifiers in aqueous based solutions. The first formed segmented linear(co)polymer chains are chain extended with a crosslinker forming acrosslinked core.

In another embodiment a simple industrially scalable process for thepreparation of star macromolecules is provided wherein the arms comprisesegments selected to induce self assembly and wherein the selfassemblable star macromolecules are suitable for use as rheology controlagents in waterborne and solvent-borne coatings, adhesives, cosmeticsand personal care compositions.

The invention is not limited to the specific compositions, components orprocess steps disclosed herein as such may vary.

It is also to be understood that the terminology used herein is only forthe purpose of describing the particular embodiments and is not intendedto be limiting.

The procedure for the preparation of star macromolecules may beexemplified by (co)polymerization of linear macromolecules, includingmacroinitiators (MI) and macromonomers (MMs), with a multi-vinylcross-linker, a divinyl crosslinker is employed in the exemplaryexamples disclosed herein, to form a core of the star. The formation ofthe core of the star can also be formed through a copolymerizationreaction wherein a monovinyl monomer is added to expand the free volumeof the core to allow incorporation of additional arms into the congestedcore forming environment or to provide sufficient free volume within thecore of the star to encapsulate functional small molecules. A moleculethat functions as an initiator and a monomer, an inimer, can also beemployed in the preparation of the core of the star macromolecule. Whenadded to the reaction it functions to form a three arm branch in thecore of the molecule and hence acts in a manner similar to the addedmonomer to increase the free volume within the star core.

The volume fraction of the core of the star can be controlled byappropriate selection of the crosslinker molecule or by conducting acopolymerization between the crosslinker and a vinyl monomer or aninimer. The composition of the core can be selected to provide anenvironment to encapsulate small molecules, such as fragrances, andcontrol the rate of diffusion of the fragrance from the self assembledthickening agent after deposition on a part of the human body.

The core of the star polymers may contain additional functionality. Thisadditional functionality can be of direct utility in certainapplications or can be employed to tether or encapsulate furtherfunctional materials such as fragrances, stimuli responsive molecules orbio-responsive molecules to the core of the star by chemical or physicalinteractions.

The star macromolecules can be prepared in dilute solution when reactionconditions and crosslinker are chosen to avoid or reduce star-starcoupling reactions.

The synthesis of multi-arm star polymers where the periphery of the starpolymers contains additional functionality is possible. Thisfunctionality can be introduced by use of an initiator comprising thedesired α-functionality in the residue of the low molecular weightinitiator remaining at the α-chain end of each arm.

An embodiment of the present invention can be exemplified by thepreparation of a multi-arm star macromolecule wherein the number of armsin the star macromolecule is between 5 and 500, preferentially between10 and 250, with segments selected to induce self assembly when the starmacromolecule is dispersed in a liquid wherein the self assemblable starmacromolecules are suitable for use as thickening agents or rheologymodifiers in cosmetic and personal care compositions at lowconcentrations of the solid in the thickened solution, preferably lessthan 5 wt %, and optimally less than 1 wt %. The dispersion medium cancomprise aqueous based systems or oil based systems.

The structure of an exemplary new thickening agent, or rheologymodifier, of one embodiment, is a multiarm segmented star macromoleculewherein the core is prepared by controlled radical polymerization usingan arm-first method. Scheme 3 provides a simple four step procedure thatcan be employed for preparation of an initial non-limiting exemplifyingcase the procedure is an atom transfer radical polymerization arm firstmacroinitiator method. In this approach the precursor of the arm(s)comprise a linear copolymer chain with a single terminal activatablegroup, as will be understood by one skilled in the art, having thisdisclosure as a guide, the activatable arm precursor will have aω-terminal functionality that under the conditions of the polymerizationprocedure can reversibly generate a radical. Scheme 3 illustrates theconcept by sequential polymerization of styrene and tBA. These monomersare purely exemplary monomers and should not limit the applicability ofthe procedure in any manner since other monomers of similar phylicitycan be employed. In Scheme 3 the polystyrene segment can be consideredthe outer shell of the star and the final poly(acrylic acid) segmentsthe inner water soluble shell and the segment formed by chain extendingthe linear copolymer macroinitiators by reaction with the divinylbenzenecrosslinker the core of the star.

Similar structures can also be prepared using the macromonomer method ora combination of the macromonomer and macroinitiator method in acontrolled polymerization process, or even through free radicalcopolymerization conducted on macromonomers, as known to those skilledin the art. [Gao, H.; Matyjaszewski, K. Chem. Eur. 12009, 15,6107-6111.]

Both the macromonomer and macroinitiator procedures allow incorporationof polymer segments prepared by procedures other than CRP [WO 98/01480]into the final star macromolecule. Polymer segments can comprisesegments that are bio-degradable of are formed from monomers preparedfrom biological sources.

As noted above the first formed ATRP macroinitiator can be prepared byconducting a sequential ATRP (co)polymerization of hydrophobic andhydrophilic monomers or precursors thereof or can be prepared by otherpolymerization procedures that provide a functional terminal atom orgroup that can be converted into an ATRP initiator with a bifunctionalmolecule wherein one functionality comprises a transferable atom orgroup and the other functionality an atom or group that can react withthe functionality first present on the (co)polymer prepared by anon-ATRP procedure. [WO 98/01480]

In aqueous solutions, the composition and molecular weight of the outershell of hydrophobes, or agents that participate in molecularrecognition, can be selected to induce self-assembly into aggregates andact as physical crosslinkers. Above a certain concentration,corresponding to the formation of a reversible three dimensionalnetwork, the solutions will behave as physical gels thereby modifyingthe rheology of the solution.

In one embodiment, the polymer compositions of the invention havesignificantly lower critical concentration for network (gel) formationcompared to networks formed with block copolymers, graft and stars witha low specific number of attached arms due to:

-   -   multi-arm structure (many transient junctions possible between        hydrophobic parts of the stars)    -   very high molecular weight of each star (5 thousand to 5 million        or higher) allows high swelling ratio of the molecules in        solution    -   molecular organization on larger scales (>1 μm)

Whereas the examples above and below describe the preparation and use ofblock copolymers as arms with a well defined transition from one segmentto the adjoining segment a segmented copolymer with a gradient incomposition can also be utilized. The presence of a gradient can becreated by addition of a second monomer prior to consumption of thefirst monomer and will affect the volume fraction of monomer unitspresent in the transition form one domain to another. This would affectthe shear responsiveness of the formed star macromolecule.

Star macromolecules with narrow polydispersity comprising arms withblock copolymer segments can be formed with as few as 5 arms byselecting appropriate concentration of reagents, crosslinker andreaction temperature.

Star macromolecules can be prepared in a miniemulsion or reverseminiemulsion polymerization system. The first formed block copolymersare used as reactive surfactants for star synthesis by reaction with aselected crosslinker in miniemulsion.

EXAMPLES

Abbre- Commercial viation Name Form Purity Source St styrene liquid 99%Sigma Aldrich tBA tertiary-butyl acrylate liquid 98% Sigma Aldrich AAacrylic acid NA NA NA (formed by deprotection) HEA hydroxyethyl acrylateliquid 96% Sigma Aldrich DEBMM diethyl 2-bromo-2- liquid 98% SigmaAldrich methylmalonate TPMA tris(2- solid 95% ATRP pyridylmethyl)amineSolutions AIBN 2,2′-Azobis(2- solid 98% Sigma Aldrichmethylpropionitrile) Sn(EH)₂ tin(II) liquid 95% Sigma Aldrich2-ethylhexanoate DVB divinylbenzene liquid 80% Sigma Aldrich TFAtrifluroacetic acid liquid 99% Sigma Aldrich THF tetrahydrofuran liquid99.9%   Sigma Aldrich NaOH sodium hydroxide solid 98% Sigma Aldrich EBiBEthyl α- liquid 98% Sigma Aldrich bromoisobutyrate Methylene chlorideliquid 99.6%   Sigma Aldrich Acetonitrile liquid 99.8%   Sigma AldrichNaCl Sodium chloride solid 99.7%   Fisher DMAEMA 2-(dimethylamino)ethylChemical methacrylate PEGMA (polyethylene glycol) methacrylate NIPAMN-isopropylacrylamide

Synthesis, Purification and Properties of Star Thickening Agent.

The initial examples of a star thickening agents with the structureshown below in FIG. 1 as structure A, are star macromolecules withPSt-b-PAA arms or PSt-b-P(HEA) arms.

Example 1 Preparation of a (PSt-b-PAA)_(X) Star Macromolecule

The simple four step procedure was developed for the preparation of apoly(acrylic acid) based star macromolecule is described in Scheme 3. 1kg of the star macromolecule with PSt-b-PtBA arms was prepared asfollows.

STEP 1: Synthesis of a polystyrene macroinitiator using ICAR ATRP. Thereaction conditions are St/DEBMM/CuBr₂/TPMA/AIBN=50/1/0.002/0.003/0.05in bulk at T=60° C., t=10.2 h. The reaction was run to ˜30% conversionresulting in the molecular weight of the hydrophobic, polystyrenesegment=1600 which is equivalent to an average degree of polymerization(DP) of 16.

The GPC trace obtained for the macroinitiator is shown in FIG. 2.

STEP 2: Synthesis of polystyrene-b-poly(t-butyl acrylate) segmentedblock copolymer macroinitiator. The reaction conditions for thesynthesis of PSt-b-PtBA macroinitiator arm are:tBA/PSt/CuBr₂/TPMA/Sn(EH)₂=200/1/0.01/0.06/0.008 in anisole (0.5 volumeeq. vs. tBA), T=55° C., t=18.0 h. A higher molecular weight precursor ofthe water soluble segment was targeted to allow significant degree ofswelling of the inner shell of the final functional star macromolecule.The final molecular weight of the poly(t-butyl acrylate) segment in theblock copolymer was ˜15,400 which is equivalent to a DP=120. The GPCcurves of the polystyrene macroinitiator and the formed block copolymermacroinitiator is shown in FIG. 3 and clearly indicates that a cleanchain extension had occurred.

STEP 3: Synthesis of the (PSt-b-PtBA)x star macromolecule.

A multi-arm star macromolecule was prepared by conducting a furtherchain extension reaction with the block copolymer macroinitiator formedin step 2. The reaction was conducted with a mole ratio of blockcopolymer to divinylbenzene of 1:12 in anisole. The reaction conditionsare: DVB/PSt-b-PtBA/CuBr₂/TPMA/Sn(EH)₂=12/1/0.02/0.06/0.1 in anisole (38volume eq. vs. DVB), T=80° C., t=21.0 h). The GPC curves and results ofthe star forming reaction are provided in FIG. 4. It can be seen that amulti-arm star macromolecule with a crosslinked core was formed. The GPCmolecular weight of the star was 102,700 with a PDI 1.29, which wouldindicate an average of six arms but this is an underestimate of theactual number of arms since the star molecule is a compact molecule.Indeed in this situation the number of arms in the star molecule isclose to 30.

The number of arms can be modified by conducting the core formingreaction with a different ratio of crosslinking agent to arm precursoror by running the reaction with a different concentration of reagents.

STEP 4: Deprotection of the (PSt-b-PtBA)x star macromolecule to(PSt-b-PAA)x star block copolymer to provide water soluble poly(acrylicacid) segments in the multi-arm star macromolecule. The PSt-b-PtBA armsof the star macromolecule were transformed to PSt-b-PAA arms using a newprocedure. Polymer was dissolved in methylene chloride andtrifluoroacetic acid to deprotect tBu groups, the reaction was performedat room temperature for 60.0 h. Then polymer was decanted and washed 3times with acetonitrile. Polymer was then solubilized in THF andprecipitated into acetonitrile. The star macromolecule was dried invacuum oven for 3 days at 50° C. The amount of polymer obtained afterpurification was 550 g, which would correspond to full conversion ofPtBA to PAA.

Example 2 Properties of (PSt-b-PAA) Star Macromolecule as a ThickeningAgent

The thickening properties of the final star macromolecule wereinvestigated in aqueous solution. 100 mg of (PSt-b-PAA) starmacromolecule was dissolved in 0.5 ml of THF and transferred to 10 ml ofwater. Solution was then neutralized with 2 ml of basic water (withNaOH). After few minutes of stirring gel was formed, see image in FIG.5.

The rheological properties of the multi-arm star built with a longerpoly(acrylic acid (PAA) hydrophilic internal core segment and a shorthydrophobic polystyrene (PSt) peripheral segment were then investigated.The viscosity of aqueous solutions containing different concentrationsof the star macromolecule vs. shear rate were measured; using aBrookfield LVDV-E, Spindle #31 (or #34, #25) at a T=25° C., and theresults are presented in FIG. 6. It is clear that even very lowconcentrations of the star macromolecule in water (<0.6 weight %) theapparent viscosity of the sample is very high (in the range of 50,000 to100,000 centipoise (cP)).

In comparison, leading thickening agents on the market for personal careproducts (e.g. natural nonionic vegetable derived liquid thickenerCrothix Liquid by CRODA or synthetic acrylate based copolymer DOWCORNING RM 2051) are used at the level of 2-5 weight % and only increasethe viscosity of a water based solution up to 5,000-20,000 cP.

FIG. 7 presences the viscosity of aqueous solution of a (PSt-b-PAA) starmacromolecule vs. concentration. The measurement was conducted on aBrookfield LVDV-E with spindle #31 (or #34, #25) at a temperature=25° C.and rate=1 RPM. It can be seen that for this particular starmacromolecule 0.3 weight % concentration of star macromolecule in wateris a minimum amount for gel formation and that higher concentrationssignificantly increase the viscosity of the resulting solution.

Tests indicated that the thickening agent provided formulations thatexhibited a lack of tackiness, a very pleasant feel on the skin.

Example 3 Properties of (PSt-b-PAA) Star Macromolecule as ThickeningAgents in Harsh Environments

The thickening properties of the final star macromolecule wereinvestigated in aqueous solution in the presence of an oxidizing agentand at high pH. FIG. 8 presents the viscosity of an aqueous solution of(PSt-b-PAA) star macromolecule and the viscosity of water/windex (1/1v/v) solution of (PSt-b-PAA) star macromolecule and FIG. 9 presents theresults obtained with Carbopol EDT 2020 in the same media. The pH of theaqueous solution was 6-7 while for the water/Windex solution pH=9-10.(Measurement of viscosity was conducted using a Brookfield LVDV-E,Spindle #31 (or #34, #25), T=25° C.) It can be seen that viscosity ofwater/windex solution is higher than that of water solution. Theperformance of (PSt-b-PAA) star macromolecule as thickening agent is notdiminished in this harsh environment presented by the windex/watersolution with a pH=9-10 resulting from the presence of high amount ofammonia-D. In comparison, the thickening properties of the leadingthickener on the market, Carbopol EDT 2020, were decreased in similarconditions and FIG. 9 shows that the viscosity of water/windex solutionis lower than that of pure aqueous solution.

It is envisioned that the poor performance of Carbopol vs. (PSt-b-PAA)star macromolecule as thickening agent in water/Windex solution is aconsequence of the high amount of ester bonds in its structure which caninteract with the ionic species present in such harsh environment or canbe even degraded. On the other side (PSt-b-PAA) star macromolecule hasonly C—C bonds, which make this thickening agent stable in water/Windexsolution and overall thickening performance is not decreased.

Example 4 Properties of (PSt-b-PAA) Star Macromolecule vs. (PAA) StarMacromolecule as Thickening Agents

A (PAA) star macromolecule was synthesized in order to compare itsproperties to those determined for the (PSt-b-PAA) star macromolecule.Synthesis of (PAA) star was performed in similar way as for synthesis of(PSt-b-PAA) star macromolecule but starting with pure PtBA arms.

The final (PAA) star had similar molecular weight, number of arms andmolecular weight distribution to the (PSt-b-PAA) star macromolecule,FIG. 10. The only one difference between two star macromolecules is theouter shell which comprises of PSt with degree of polymerization 16 in(PSt-b-PAA) star macromolecule whereas this star macromolecule possespure PAA homo-polymeric arms. FIG. 11 presents the viscosity of aqueoussolutions of (PSt-b-PAA) star and (PAA) star macromolecules. Themeasurement was conducted using a Brookfield LVDV-E fitted with a #31spindle at a temperature=25° C. and pH=7. It can be seen that viscosityof star macromolecule with a hydrophobic outer shell has very strongthickening properties, where the pure (PAA) star has low thickeningeffect on water.

Therefore one can conclude that in order to thicken aqueous based mediathe proposed multi-arm star macromolecules have to have a blockystructure, with a hydrophilic inner shell and a hydrophobic outer shell.Without wishing to be limited by a proposed mechanism we believe theseresults in aqueous media can be explained by the induced self-assemblyof the hydrophobic segments into aggregates, the hydrophobes act as“junctions” between aggregates, and above a certain concentration, athree-dimensional reversible physical network is formed with a behaviorsimilar to conventional gels.

Example 5 (PSt-b-PAA) Star Macromolecule as Thickening and EmulsifyingAgent

Due to its very well-defined structure, (PSt-b-PAA) multi-arm starmacromolecule may act not only as a thickening agent but also asefficient emulsifying agent. FIG. 12 presents images demonstrating theemulsifying properties of (PSt-b-PAA) star macromolecule. Firstphotograph shows mixture of water with 2 volume % of pure lemon oil.After vigorous mixing, water and oil quickly separated into two phases.The second photograph presents water with 2 volume % of lemon oil and0.6 weight % of thickening agent. After vigorous mixing, the phaseseparation did not occur and thicken properties did not decrease.Solutions were shaken for 1 min and photographs were taken 2 h aftermixing.

Its hydrophobic core (as well as hydrophobic outer shell) may act as astorage place for small organic molecules (e.g. vitamins, fragrances,sunblock agents, etc.). This provides for the possibility for deliveryof functional organic molecules, e.g. fragrance for slow release or UVabsorbing molecules in sunscreens to any part of the body in a pleasantfeeling emulsion.

In order to provide an equivalent response for non-polar media thephylicity of the inner and outer shells would have to be reversed.

Example 6 Mikto-Arm Star Macromolecules

A multi-arm star macromolecule was synthesized. The procedures forforming the arms PSt-b-PtBA and PtBA were similar to that described inExample 1. Next, two different arms were crosslinked together to form astar macromolecule. Reaction conditions for core forming crosslinkingreaction: DVB/[PSt-b-PtBA/PtBA]/CuBr₂/TPMA/Sn(EH)2=17/1/0.02/0.06/0.2 inanisole (38 volume eq. vs. DVB), (1667 ppm of Cu) T=95° C., t=53.0 h,PSt-b-PtBA/PtBA=1/4. Next, PtBA was transformed to PAA by deprotectionwith acid as described in Step 4 in Example 1.

FIG. 13 shows the GPC curves of the arms and the formed mikto-arm starmacromolecule before and after purification by precipitation. Schematic13B shows a representation of such a mikto-arm star macromolecule.

Synthesis of stars with lower amounts of the outer PSt block wassuccessfully performed. Two stars were synthesized, one with 50% and onewith 20% of PSt-b-PAA arms and 50% and 80% pure PAA arms (WJ-08-006-234and WJ-06-235) by the procedures detailed above. Studies show that thesestar macromolecules can be dispersed directly in warm water. Thickeningproperties of these two new stars were as good as first exemplary starwith 100% of PSt-b-PAA arms.

Stars with different outer hydrophobic shells can be prepared. Oneexample that provides an outer shell which exhibits a Tg below usetemperature is a star prepared with a PnBA outer shell.

Another approach which can reduce the cost of the preparing an outerhydrophobic shell is conversion of commercially available α-olefins toan ATRP initiator by reaction with a halo-alky(meth)acrylylhalide.

Example 7 Stars with Different Hydrophobic Segments

One parameter which may significantly change viscosity of thickeningagent as well as its interaction with surfactant in shampoo formulationsis the type of hydrophobic unit capped at the peripheral end of afraction of the arms of the star macromolecule. Two additional starswere synthesized in order to compare to (PSt₁₆-PAA₁₂₀)_(X) (beforedeprotection: M_(n,app)=102,700 g/mol, PDI=1.29) star macromolecule.

These stars include:

-   -   A) C₁₈-PAA₁₄₆)_(X): M_(n,app)=95,600 g/mol, PDI=1.48,    -   B) C₁₂-PAA₁₃₄)_(X): M_(n,app)=113,900 g/mol, PDI=1.53,

Each star was prepared in three steps:

-   -   i) preparation of PtBA arm,    -   ii) crosslinking arms into star macromolecule,    -   iii) deprotection of tBu groups. All of the stars had relatively        low PDI with low amount of unreacted arms (<15 wt %).

A) A new PtBA macroinitiator was prepared from an initiator containing alinear C₁₈ alkyl chain for preparation of the (C₁₈-PAA₁₄₆)_(X) star. Thesynthesis of this arm precursor C₁₈-PtBA-Br was accomplished using ARGETATRP of tBA using C₁₈ alkyl chain functionalized EBiB. The conditionsand properties of synthesized polymer are shown in Table 1.

TABLE 1 Experimental conditions and properties of PtBA prepared by ARGETATRP.^(a) Molar ratios Cu Time Conv. Entry tBA I CuBr₂ L RA [ppm] (min)(%) M_(n,theo) ^(b) M_(n,GPC) M_(w)/M_(n) 08-006- 300 1 0.015 0.06 0.150 1380 47 18200 19700 1.19 160 TPMA ^(a)I = C₁₈-EBiB, L = Ligand, RA =reducing agent = Sn(EH)₂; [tBA]₀ = 4.67M; T = 60° C., in anisole (0.5volume equivalent vs. monomer); ^(b)M_(n, theo) = ([M]₀/[C₁₈-EBiB]₀) ×conversion

This macroinitiator was than crosslinked using DVB into a starmacromolecule. After deprotection of tBu groups by stirring the reactionfor 3 days in the presence of TFA resulting in transformation to PAAunits star was precipitated from CH₂Cl₂. The viscosity of resulting(C₁₈-PAA)x star and the (C₁₂-PAA)x star can be compared to (PSt-b-PAA)xin water and shampoo formulations.

Example 8 Stars with an Inner P(HEA) Shell

P(HEA) star macromolecules that comprise water soluble non-ionizablehydrophilic segments selected to make the star macromolecules compatiblewith solutions further comprising dissolved/dispersed salts that areadditionally stable over a broad range of pH.

The PSt-b-PHEA arm precursor was prepared using ICAR ATRP. Conditionsfor the polymerizations and characterization of the resulting polymerare shown in Table 2. Polymerization was well controlled andwell-defined block copolymer was prepared with relatively low (PDI=1.26and 1.20). This is the first example of successful ICAR ATRP foracrylate type monomer. PSt-b-PHEA arm precursor was purified byprecipitation into ethyl ether and dried under vacuum over two days at50° C.

TABLE 2 Experimental conditions and properties of PSt-b-PHEA prepared byICAR ATRP.^(a) Molar ratios Cu Time Conv. Entry HEA I CuBr₂ L RA [ppm](min) (%) M_(n,theo) ^(b) M_(n,GPC) M_(w)/M_(n) 08-006- 200 1 0.04 0.040.1 200 1200 63 16100 30400 1.26 155 TPMA 08-006- 300 1 0.05 0.05 0.05167 1230 54 20300 42300 1.20 158 TPMA ^(a)I = PSt (08-006-29, M_(n) =1600 g/mol, PDI = 1.20), L = Ligand, RA = reducing agent = AIBN; [HEA]₀= 5.44M; T = 65° C., in DMF (0.7 volume equivalent vs. monomer);^(b)M_(n, theo) = ([M]₀/[PSt]₀) × conversion.

Different crosslinking agents were investigated, including DVB and inrun 08-006-159 di(ethylene glycol)diacrylate (DEGlyDA) and in run08-006-161 DEGlyDA with small amount of HEA monomer. The reaction wasnot fully controlled when conversion of the added divinyl crosslinkerwas driven to high conversion as a consequence of star-star corecoupling reactions resulted in gel formation. However at lowerconversion of the crosslinker and under more dilute conditions starmacromolecules were formed.

Example 9 Preparation of a (PSt₁₅-b-PAA₂₉₀/PAA₁₅₀)_(≈30) Miktoarm StarMacromolecule (Referenced Herein as Advantomer)

The simple four step procedure was developed for the preparation of apoly(acrylic acid) based miktoarm star macromolecule and is described inScheme 4. 1 kg of the miktoarm star macromolecule with PSt-b-PAA and PAAarms (molar ratio of arms 4/1) was prepared as follows.

Step 1: Synthesis of a Polystyrene Macroinitiator (PSt) Having 15 DP

A polystyrene macroinitiator was formed using ICAR ATRP by introducingthe following components into the reaction vessel at the following molarratio: St/DEBMM/CuBr₂/TPMA/AIBN=50/1/0.002/0.003/0.05 in bulk at T=60°C., t=10.2 h. The reaction was run to ˜30% conversion. The resultingreaction product was purified to obtain the PSt in powder form. Aportion of the PSt powder was dissolved in THF and passed through theGPC column. The GPC trace obtained for the macroinitiator is shown inFIG. 2. The measured molecular weight of the hydrophobic, polystyrenesegment=1600 which is equivalent to an average degree of polymerization(DP) of about 15-16 and the PDI was measured to be 1.24.

Step 2: One-Pot Synthesis of Polystyrene-b-Poly(t-Butyl Acrylate) andPoly(t-Butyl Acrylate) Macroinitiator

The following components were introduced into the reaction vessel in thefollowing molar ratio: tBA/PSt (from step1)/CuBr₂/TPMA/Sn(EH)₂=200/0.2/0.01/0.06/0.1, in anisole (0.5 volume eq.vs. tBA), T=55° C. About 2.0 hours after the reaction was initiated, theconversion of the tBA reached about 6% and a portion of the PSt-b-PtBAwas recovered and measured by GPC with the following resultsM_(n)=19,800 g/mol; PDI=1.16. It was determined that the followingPSt₁₅-b-PtBA₁₄₀ copolymeric block was obtained. Then, 0.8 molar ratioamount, relative to the initially introduced components, of Ethyl2-bromoisobutyrate (EBiB) was injected into the polymerization mixture.The reaction was continued and stopped after about 19.8 h. The reactionproduct was purified and the product was analyzed by GPC. Based on theGPC measured values the final molecular weight of the product wasdetermined to be poly(t-butyl acrylate) segment in the block copolymerwas ˜37,200 g/mol (PSt₁₅-b-PtBA₂₉₀) and the molecular weight ofpoly(t-butyl acrylate) initiated from EBiB was 19,200 g/mol which isequivalent to a DP=150. The overall molecular weight of mixture of armsresulted in M_(n)=20,800 g/mol and PDI=1.27. The GPC curves of thepolystyrene macroinitiator and the mixture of formed block copolymerarms PSt₁₅-b-PtBA₂₉₀ and poly(t-butyl acrylate) arms PtBA₁₅₀ are shownin FIG. 23. The signal from block copolymer is overlapping with signalfrom homopolymer but this result clearly indicates that a clean chainextension from PSt had occurred.

Step 3: Synthesis of the (PSt-b-PtBA/PtBA)_(≈30) Miktoarm StarMacromolecule

A mikto multi-arm star macromolecule was prepared by conducting afurther chain extension reaction with the block copolymer andhomopolymer macroinitiators formed in step 2. The reaction was conductedwith a mole ratio of macroinitiators to divinylbenzene of 1:16 inanisole. The following components were introduced into the reactionvessel in the following molar ratio: DVB/[PSt-b-PtBA/PtBA] (from step2)/CuBr₂/TPMA/Sn(EH)₂=16/1/0.02/0.07/0.15 in anisole (38 volume eq. vs.DVB), T=95° C., t=20.6 h. The reaction product was purified and theproduct was analyzed by GPC. The GPC curves and results of the starforming reaction are provided in FIG. 24. It can be seen that amulti-arm star macromolecule with a crosslinked core was formed. The GPCapparent molecular weight of the star was 109,400 with a PDI 1.52, whichwould indicate an average of six arms but this is an underestimate ofthe actual number of arms since the star molecule is a compact molecule.Indeed in this situation, the number of arms in the star molecule isclose to 30.

The number of arms can be modified by conducting the core formingreaction with a different ratio of crosslinking agent to arm precursoror by running the reaction with a different concentration of reagents.

Step 4: Deprotection of the (PSt-b-PtBA/PtBA) to (PSt-b-PAA/PAA)

Deprotection of the (PSt-b-PtBA/PtBA)_(≈30) star macromolecule to(PSt-b-PAA/PAA)_(≈30) star block copolymer to provide water solublepoly(acrylic acid) segments in the mikto multi-arm star macromolecule.The PSt-b-PtBA/PtBA arms of the miktoarm star macromolecule weretransformed to PSt-b-PAA/PAA arms with the following procedure. Polymerwas dissolved in methylene chloride and trifluoroacetic acid todeprotect tBu groups, the reaction was performed at room temperature for60.0 h. Then polymer was decanted and washed 3 times with acetonitrile.Polymer was then solubilized in THF and precipitated into acetonitrile.The star macromolecule was dried in vacuum oven for 3 days at 50° C. Theamount of polymer obtained after purification was 550 g, which wouldcorrespond to full conversion of PtBA to PAA.

Test Results Table—comparing the star macromolecule formed in example 9(Advantomer) against commerically available thickening agent, CarbopolETD 2020.

Advantomer (as formed in Properties Example 9) Carbopol ETD 2020 DynamicViscosity 25,830 cP @ 0.2 wt % 48,000 cP @ 0.2 wt % (@1 rpm)Salt-Induced 87.8% @ 0.7 wt % 52.4% @ 0.4 wt % Break Value pH-InducedBreak Value 99.3% @ 0.4 wt % 12.6% @ 0.2 wt % Sheer-Thinning Value 32.7@0.2 wt % 12.9@ 0.2 wt % Strong Gel Yes Yes Emulsion Value >12 hours <5min. HLM >0.96 N/A

Test Procedures

Sample Preparation

Aqueous gel compositions were prepared at various concentrations (e.g.,0.2 wt. %, 0.25 wt %, 0.4 wt. % 0.6 wt. %, 0.7 wt. % and 1.0 wt. %) byheating and stirring, as necessary (e.g., vigorously mixing at atemperature of about 60° C.) the sample material (e.g., a starmacromolecular powder or Carbopol ETD 2020) into water pH adjusted, asnecessary, (e.g., a pH of about 7.5 with addition of sodium hydroxide)to obtain a homogenous mixture.

Dynamic Viscosity & Shear-Thinning Test Procedure

A portion of the sample preparation was introduced into a BrookfieldLVDV-E Digital Viscometer, using spindle #31 for mixing, at STP, over awide range of rates (e.g, 0.3-100 rpm) and the shear rate and viscositywas recorded. Viscosity measurements were taken in the followingsequence without stopping the instrument, 0.3, 0.5, 1, 2, 5, 10, 20, 30,50, and 100 rpm. The dynamic viscosity was determined as the viscosityin centipoise (cP) at 0.3 rpm. A shear-thinning value was determined bydividing the dynamic viscosity value at 0.3 rpm by the dynamic viscosityvalue at 20 rpm.

Viscosity [cP] Advantomer Carbopol Shear Rate [s⁻¹] rpm 0.2 wt % 0.2 wt% 0.102 0.3 67100 85000 0.17 0.5 46980 65600 0.34 1 25830 48000 0.68 213880 23300 1.7 5 6580 15800 3.4 10 3620 10400 6.8 20 2050 6600 10.2 301480 4800 17 50 1000 3300 34 100 690 2250

Salt-Induced Break Test Procedure

A portion of the sample preparation was introduced into 20 ml glassscintillation vial. A measured portion of NaCl was added into the vial(e.g., 0.05 wt. % relative to the total weight of the sample in thevial. After the NaCl addition was complete, the vial was closed andshaken for 10 min. Then, the viscosity of the sample was measured inaccordance with the Dynamic Viscosity & Shear-Thinning Test Procedure,above, and the dynamic viscosity at 1 rpm was recorded. This procedurewas repeated for differing concentrations of NaCl. The results arepresented in FIGS. 18 & 22. The salt-induced break value, in percent, isdetermined by the following equation:

Initial Dynamic Viscosity (0% NaCl)−Dynamic Viscosity (0.05 wt. %NaCl)/Initial Dynamic Viscosity (0% NaCl)×100%.

pH Efficiency Range Test Procedure

An aqueous gel composition at 0.4 wt. % was prepared for the starmacromolecule of Example 9, at a starting pH of around 5 and a separateaqueous gel composition at 0.2 wt. % aqueous gel composition of CarbopolETD 2020, at a starting pH of around 3, was prepared by mixing andheating, as necessary (e.g., vigorous mixing at a temperature of about60° C.). Then, the viscosity of the sample was measured in accordancewith the Dynamic Viscosity & Shear-Thinning Test Procedure, above, andthe dynamic viscosity at 1 rpm was recorded. This procedure was repeatedfor differing pH values, adjusted by addition of sodium hydroxide. Theresults are presented in FIG. 19. The ph-induced break value, inpercent, is determined by the following equation:

Dynamic Viscosity (at 1 rpm) at pH 7.5−Dynamic Viscosity (at 1 rpm) atpH 5/Dynamic Viscosity (at 1 rpm) at pH 7.5×100%.

Emulsion Test Procedure

340 mL of water was added to a 500 ml beaker and stirred vigorously withan overhead stirrer. 1.6 g of the material to be tested for emulsifyingeffect was added and heated to 80 C. The solution was pH adjusted with400 mg of NaOH and stirring continued until a homogeneous gel wasobtained. 60 ml sunflower oil was added while vigorous stirring wascontinued with an overhead stirrer at 80 C for 10 min or untilhomogenous emulsion is obtained. The mixture was allowed to cool to roomtemperature. Once the system cools to room temperature start timer. Theemulsion value is the time, in minutes, it takes for the system to formtwo visible layers (phase separation).

Strong Gel Test Procedure

10 ml portion of the sample preparation material was introduced into a20 ml glass scintillation vial. After the transfer was complete, thevial was placed on a surface and remained undisturbed for about 20minutes at STP. The vial was then gently inverted (turned-upside down)and placed on the surface and a timer started. If after 5 minutes, thereis no visible flow then the sample is said to be a strong gel.

Hydrophilic-Lipophilic (HLB) Arm/Segment Calculation

HLB=20*Mh/M

where Mh is the molecular mass of the hydrophilic portion of thepolymeric arm or segment, and M is the molecular mass of the wholepolymeric arm or segment.

Hydrophilic-Lipophilic Macromolecule Calculation

$\mspace{79mu} {{H\; L\; M} = {{\text{?}\mspace{14mu} {divided}\mspace{14mu} {by}\mspace{14mu} 0.3\mspace{14mu} {MW}_{core}} + {\sum\limits_{n = 1}^{n - m}{MW}_{n}}}}$?indicates text missing or illegible when filed

where

-   -   MW_(n) is the molecular weight for the respective arm,    -   HLB_(n) is the HLB, as calculated from the HLB arm calculation,        for the respective arm, and    -   MW_(core) is the molecular weight for the core, and    -   M is the total number of arms.

The disclosed star macromolecules can find utility in a spectrum ofapplications including, but not limited to; personal care: includingshampoos/conditioners, lotions, serums, creams, solids, gelly,cosmetics: including mascara, blush, lip stick, powders, perfumes andhome care: including cleaners for windows, household and work surfaces,toilet areas, laundry, and in dish and dishwasher applications.

1. A star macromolecule represented by Formula X: [(P1)_(q1)-(P2)_(q2)]_(t)-Core-[(P3)_(q3)]_(r)  Formula X wherein: Core represents a crosslinked polymeric segment; P1 represents a homopolymeric segment comprised of repeat units of monomeric residues of polymerized hydrophobic monomers; P2 represents a homopolymeric segment comprised of repeat units of monomeric residues of polymerized hydrophilic monomers; P3 represents a homopolymeric segment comprised of repeat units of monomeric residues of polymerized hydrophilic monomers; q1 represents the number of repeat units in P1 and has a value between 1 and 50; q2 represents the number of repeat units in P2 and has a value between 30 and 500; q3 represents the number of repeat units in P3 and has a value between 30 and 500; r represents the number of homopolymeric arms covalently attached to the Core; t represents the number of copolymeric arms covalently attached to the Core; and wherein the molar ratio of r to t is in the range of between 20:1 and 2:1.
 2. The star macromolecule of claim 1, wherein the one or more star macromolecules have a molecular weight of between 150,000 g/mol and 600,000 g/mol.
 3. The star macromolecule of claim 1, wherein the sum total number of arms (r+t) is between 15 and
 45. 4. The star macromolecule of claim 1, wherein the molar ratio of r to t is in the range of between 8:1 and 3:1.
 5. The star macromolecule of claim 1, wherein both q2 and q3 have a value greater than 100, and wherein q2 is greater than q3.
 6. The star macromolecule of claim 1, wherein the arms represented by [(P1)_(q1)-(P2)_(q2)] have an HLB value greater than
 18. 7. The star macromolecule of claim 1, wherein the P1 homopolymeric segment is a hydrophobic homopolymeric segment having an HLB value of less than
 8. 8. The star macromolecule of claim 1, wherein the core comprises a hydrophobic crosslinked polymeric segment.
 9. The star macromolecule of claim 1, wherein the star macromolecule is a water soluble mikto star macromolecule.
 10. The star macromolecule of claim 1, wherein the star macromolecule, when dissolved in water at a concentration of at least 0.2 wt. %, forms a clear, homogeneous gel having a viscosity of at least 20,000 cP.
 11. A star macromolecule having a molecular weight of between 150,000 g/mol and 600,000 g/mol that forms a clear, homogeneous gel when dissolved in water at a concentration of at least 0.2 wt. %; wherein the gel has: i) a dynamic viscosity of at least 20,000 cP; ii) a salt-induced break value of at least 60%; iii) a shear-thinning value of at least 10; and/or iv) an emulsion value of greater than 12 hours.
 12. The star macromolecule of claim 11, wherein the gel-forming star macromolecule has a viscosity of greater than 40,000 cP at a pH between 6 to
 11. 13. The star macromolecule of claim 11, wherein the gel-forming star macromolecule has a viscosity of less than 5,000 cP at a shear rate of 4 sec⁻¹.
 14. The star macromolecule of claim 11, wherein the gel-forming star macromolecule has a PDI of less than 2.5.
 15. The star macromolecule of claim 11, wherein the gel-forming star macromolecule is a water-soluble mikto star macromolecule.
 16. The star macromolecule of claim 11, wherein the gel-forming star macromolecule has between 15 to 45 arms.
 17. The star macromolecule of claim 11, wherein the arms of the gel-forming star macromolecule comprise hydrophilic homopolymeric arms and copolymeric arms, comprising hydrophilic polymeric segments and hydrophobic polymeric segments.
 18. The star macromolecule of claim 17, wherein the arms of the gel-forming star macromolecule have an HLB of between 18 and
 20. 19. An emulsion comprising: a water-soluble star macromolecule having: i) a molecular weight of at least 150,000 g/mol; and ii) a dynamic viscosity of at least 20,000 cP at a concentration of 0.4 wt. %.
 20. The emulsion of claim 19, wherein the emulsion is an emulsifier-free emulsion. 